Given :
The length of the metal is 20 inches longer than the width.
But we fold up 4-inch flaps on each side, so the height of the box is 4 inches, and the length and width will each decrease by 8 inches (4 inches on each side). Since the length and width decrease by the same amount, the length will still be 20 inches longer than the width.
Explanation :
So the equations would be:

The volume is determined as

Substitute the values

Solve the quadratic equation.

Since the width can't be negative, the width of the box is 16 and the length is l= (16 + 20)=36.
But remember, the length and width of the piece of metal are each 8 inches longer than the box, so it was 24 inches by 44 inches.