Question 866137
Let length be L and width be W

L x W = 273 ---(1)
L - W = 8 ---(2)

Rearranging (2),
L = 8 + W   ---(3)

Substitute (3) into (1)
(8+W) x W = 273
8W + W^2 = 273
W^2 + 8W - 273 = 0
(W+21)(W-13) = 0
W=-21(reject) or W=13

Using (3),
L=8+13=21