.70 * x = 9.1
.70/.70 * x = 9.1/.70
x = 13
The answer would be approximately 9 inches but the real number is 9.42 So B is the answer. I hope this helped ^^
So hmm notice the picture below
thus, the perimeter of the gutter is just w + w + l, or 2w +l
thus

take the derivative of A(w), zero it out, check any critical points in the interval of (0, 22), for a maxima
recall, the aluminum sheet is just 22inches long, thus, whatever the "depth" or "w" is, has to be more than 0, and less than 22