2L + 2W = 282 (the perimeter), which is simplified to L + W = 141, (1) L - W = 45. (2) --------------------------Add the equations to eliminate W. You will get 2L = 141 + 45 = 186 ====> L == 93. Then from (1) W = 141 - L = 141 - 93 = 48. Answer. The dimensions are 93 ft and 48 ft.
L + W + L + W = 282 (perimeter) (W+45) + W + (W+45) + W = 282 4W + 90 = 282 ====> 4W = 282 -90 = 192 ====> W == 48. The same answer.