Let length be L and width, W
Then: 2(L + W) = 146______2(L + W) = 2(73)_____L + W = 73______W = 73 - L ------ eq (i)
Also, L = 3W - 7 ------- eq (ii)
L = 3(73 - L) - 7 ------ Substituting 73 - L for W in eq (ii)
L = 219 - 3L - 7
L + 3L = 219 - 7
4L = 212
L, or length =