30 POINTS Marie here! Im giving BRAINLIEST and THANKS and FIVE STARS to the person who answers this question and explains it! How much miles is race track if the racers did 500 miles in 200 laps?

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?