The Israelites lived in Egypt for a total of 430 years:-
Exo 12:40
Now the sojourning of the children of Israel, who dwelt in Egypt, was four hundred and thirty years.
Exo 12:41 And it came to pass at the end of the four hundred and thirty years, even the selfsame day it came to pass, that all the hosts of the LORD went out from the land of Egypt.
Exo 12:42 It [ie Passover]is a night to be much observed unto the LORD for bringing them out from the land of Egypt: this is that night of the LORD to be observed of all the children of Israel in their generations.
Exo 12:43 And the LORD said unto Moses and Aaron, This is the ordinance of the passover:
The Israelites were enslaved ("afflicted") 400 years:-
Gen 15:13
And he [God] said unto Abram, Know of a surety that thy seed [descendants of his son Israel, ie Israelites] shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years;
Gen 15:14 And also that nation, whom they shall serve, will I judge: and afterward shall they come out with great substance.
This means that for the first 30 years the Israelites were treated well, but not for the remaining 400 years.
To get a brief account of events , read the summary in Acts chapter 7 : ( the entire account is basically from Genesis 15 to Exodus 15, so Acts is much shorter ).
(1). God prophesied that the then-childless Abraham's grandchildren and their descendants would be enslaved and oppressed for 400 years (verse 6).
(2). One pharoah showed favour to Joseph by making him Prime Minister of Egypt (verse 10).
(3). The Israelites grew in population (verse 17) .
(4). Another pharoah "arose who did not know Joseph" after Joseph died (verse 18; Exodus 1:8) This pharoah did not know Joseph personally: it does not mean that he did not know of Joseph at all, let alone his greatness and achievements, because he died at 110 (Genesis 50:26) and was embalmed. (You don't embalm someone you don't know of).
(5). Joseph died at 110, and he was about 40 when he was elevated to power and brought his father and brothers to Egypt, so he died about 70 years after the start of the sojourn in Egypt.
(6). It helped to understand things when it was discovered by scholars and historians that Joseph was made Prime Minister by one of the non-Egyptian Hyskos pharoahs, who were hated by the Egyptians and later thrown out of Egypt by force. Joseph reminded this pharoah of Egypt's subjugation and humiliation by the Hyskos foreigners, and this pharoah did not want to know this Hyskos-appointed Joseph.
(7). Moses was born 80 years before the end of the slavery of the Israelites (verse 20, 23, 30, 36.)
Act 7:1 Then the high priest said, Then do you so hold these things?
Act 7:2 And he [Stephen] said, Men, brothers, and fathers, listen: The God of glory appeared to our father Abraham when he was in Mesopotamia, before he lived in Haran.
Act 7:3 And He said to him, "Go out from your land and from your kindred, and come into a land which I shall show you."
Act 7:4 Then he came out of the land of the Chaldeans and lived in Haran. And from there, when his father was dead, he moved into this land in which you now dwell.
Act 7:5 And He gave him no inheritance in it, no, not even a foot-breadth. And He promised that He would give it to him for a possession, and to his seed after him, there being no child to him.
Act 7:6 And God spoke in this way, that his [Abraham's] seed [ descendants of his grandson Israel, ie Israelites] would be a tenant in another land, and that they [ie that other land] would enslave it [ie the future nation of Israel] and oppress it four hundred years.
Act 7:7 And God said, "I will judge the nation to whom they shall be in bondage," and "after these things they will come out and will serve Me in this place."
Act 7:8 And He gave him the covenant of circumcision. And so Abraham fathered Isaac and circumcised him the eighth day. And Isaac fathered Jacob, and Jacob the twelve patriarchs.
Act 7:9 And being jealous of Joseph, the patriarchs sold Joseph into Egypt. But God was with him [Joseph]
Act 7:10 and plucked him out from all his afflictions, and He gave him favor and wisdom over against Pharaoh king of Egypt. And he [pharoah] appointed him [Joseph] governor over Egypt and all his household.
Act 7:11 But a famine came over all the land of Egypt and Canaan, and a great affliction. And our fathers found no food.
Act 7:12 But hearing grain was in Egypt, Jacob sent out our fathers first.
Act 7:13 And at the second time Joseph was made known to his brothers, and Joseph's race was made known to Pharaoh.
Act 7:14 And seeing, Joseph called his father Jacob, and all his kindred, seventy-five souls.
Act 7:15 And Jacob went down into Egypt and died, he and our fathers,
Act 7:16 and were carried over into Shechem. And they were laid in the tomb that Abraham bought for a price of silver from the sons of Emmor the father of Shechem.
Act 7:17 But as the time was drawing near, of the promise which God had sworn to Abraham, the people grew and multiplied in Egypt,
Act 7:18 until another king arose who did not know Joseph.
Act 7:19 Dealing subtly with our race, this one oppressed our fathers, causing their infants to be exposed, so as not to be left alive.
Act 7:20 In this time Moses was born, and was beautiful to God, who was brought up three months in his father's house.
Act 7:21 And he being cast out, Pharaoh's daughter took him up and reared him for a son to her.
Act 7:22 And Moses was learned in all the wisdom of the Egyptians and was mighty in words and in deeds.
Act 7:23 And when a period of forty years was fulfilled to him, it arose in his heart to look upon his brothers, the sons of Israel.
Act 7:24 And seeing one being wronged, he defended him. and avenged him who was oppressed and struck the Egyptian.
Act 7:25 For he thought his brothers would understand that God would give them deliverance by his hand. But they did not understand.
Act 7:26 And the next day he appeared to them while fighting. And he urged them to peace, saying, Men, you are brothers, why do you wrong one another?
Act 7:27 But he who wronged his neighbor thrust him away, saying, Who made you a ruler and a judge over us?
Act 7:28 Will you not kill me as you did the Egyptian yesterday?
Act 7:29 And Moses fled at this word, and became a temporary resident in the land of Midian, where he fathered two sons.
Act 7:30 And forty years being fulfilled to him, the Angel of the Lord appeared to him in the desert of Mount Sinai in a flame of fire in a bush.
Act 7:31 And seeing it, Moses marveled at the sight. And as he drew near to see, the voice of the Lord came to him:
Act 7:32 saying, "I am the God of your fathers, the God of Abraham, and the God of Isaac, and the God of Jacob." But Moses trembled and dared not look.
Act 7:33 Then the Lord said to him, "Loosen the sandal on your feet, for the place where you stand is holy ground."
Act 7:34 "I have seen, the affliction of My people in Egypt, and I have heard their groan; and I came down to pluck them out. And now come, I will send you into Egypt."
Act 7:35 This Moses whom they refused, saying, Who made you a ruler and a judge? God has sent this one to be a ruler and a redeemer by the hand of the Angel who appeared to him in the Bush.
Act 7:36 He [Moses] brought them out after he had worked wonders and miracles in the land of Egypt and in the Red Sea and in the wilderness forty years.