Andrew paid $72 as bike rental charges. If he is billed at $8 an hour, how many hours has he used the bike for?(plz help)

I'll give brainliest if you answer right : )

Find the solution of this system of equation -7x+y=-20 9x-3y=36

Kayla wants to find the width, ab, of a river. she walks along the edge of the river 65 ft and marks point c. then she walks 25 ft further and marks point d. she turns 90° and walks until her location, point a, and point c are collinear. she marks point e at this location, as shown. (a) can kayla conclude that δ and δ are similar? why or why not? (b) suppose de = 15 ft. what can kayla conclude about the width of the river?