To solve the problem, use the Volume formula:
     V = L x W x H (equation 1)
Since length is twice of width, it is written as:     
     L = 2W (equation 2)
Then, substitute the known values,
Solution:     
     160 cu.in = 2W in x W in x 5 in
     160 cu.in /5 in = 2W sq.in
     32 sq.in /2 = W sq. in
     16 = W sq.in
   √16 = W
    W = 4
Since there is now a value for width, substitute width in equation 2 to get the length.
     L = 2(4)
     L = 8
The width of the box is 4 inches while the length is 8 inches.