A Piece of Sheet Metal, 9 Inches Wide, Is Bent $\quad 5$

A piece of sheet metal, 9 inches wide, is bent to form the gutter shown in the illustration.If the cross-sectional area is 10 square inches, find the depth of the gutter.

A) 2 in
B) 3 in
C) $\quad 5$ in
D) $\quad 4$ in