How do I solve this problem?

Question

You construct an open box from a square piece of material by cutting seven centimeter (denoted by h) squares from the corners and turning up the sides. The volume of the box is 448 cubic centimeters. Find the dimensions of the square piece of material that you need to construct the box.

Answer 1

The length of the box is x-14

the width of the box is also x-14

the height of the box is 7

7(x-14)^2 = 448

(x-14)^2 = 64

x-14 = 8 or x-14 = -8

x=22 or x = 6

x=6 however results in negative measures.

the original square is 22 by 22.

the dimensions of the box are 8 x 8 x 7