Rectangle perimeter formula is A=2(w+l)
We would take length as “x”.
Then width would be x-8, in case that it is 8 inches less than length.
After that, we would switch parameters in formula and we would get:
A = 2 (w+l)
144 = 2*(x-8+x)
144 = 2*(2x-8)
144 = 4x - 16 ((2*2x)-(2*8))
144 + 16 = 4x
160 = 4x
X = 160:4
X = 40.
Then length is 40, and width is 40-8=32.