Brainliest + points! can you solve the problem and why is choice c, 500 is correct? explain so i can understand my mistake!

Using the quadratic formula find the zeros of the given polynomial -5x^2+3x-11

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?

Divide. write in the simplest form. 4 1/6 divided by 10