What is the value of a in the equation 3a+b = 54, when b = 9?
15
18
21
27

Can someone me do math because i am having a breakdown rn because i don’t get it

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?

If the scale factor between two circles is 2x/5y what is the ratio of their areas?