I need answer to both pls, and pls say how to choose the most brainliest i am new

What is the missing step in this proof ?

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

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?