The equator is a mathematical line; it has no width.
Quito's latitude is about 12.5 minutes south, corresponding roughly to 12.5 nautical miles south of the equator, or roughly 13 statue miles.
A degree of Latitude is 69 miles
The circumference of the Earth at the equator is 24901.55 miles (40075.16 km).
Scientists don't know. They are measuring it by light years, not miles.