Use parentheses, then brackets, then parentheses, then brackets, and so on.
Word (word [word], word [word (word)])
probably
(a + 5) (a - 5) = a2 - 25
Brackets are used in such cases where parentheses are inside another seperste problem Ex. 7^2[6/(4+3^3)+5]=?
you first solve the inside of the bracket and then do the inside answer with the outside numbers.
2x(3x-5) = 6x2-10x