Find the solution of each equation if the replacement sets are a= { 4,5,6,7,8 } and b= { 9,10,11, 12,13 }. 4a - 8 = 16

Based on what i know about mean, this doesn't add up.

41/2 - 1 1/3 what is the answer as a fraction?

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?