What is −2√20 − √125 in simplest radical form?

Iam so stuck. what is the worked out answer for this question?

Graph y ≥ -x^2 - 1. click on the graph until the correct graph appears.

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?