If a pair of shoes costs a retailer $24 and he sells them for $39.60, what is his rate of profit

I’m stuck on this i don’t understand.

Choose all answers that apply: a) ab and a’b’ are one the same line. b) quadrilaterals abcd and a’ b’ c’ d’ have the same perimeters. c) points a and a’ have the same coordinates. d) none of the above

How can we find the measure of an exterior angle if we know the measurement of an interior angle