Set up a system of equations:
2l + 2w = 72
l = 2w
Solve the system using substitution:
2(2w) + 2w = 72
Solve for w:
4w + 2w = 72
—> 6w = 72
—> w = 12
Plug in the value for ‘w’ in the second equation:
l = 2(12)
—> l = 24
The width is 12.
The length is 24.