Please help with step by step instructions for how to solve for a and b​

Question 5 spring semester final exam math evaluate

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much

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?