Answer:
265 ft long, 165 ft wide
Explanation:
Let w represent the width of the base. Then the length is 2w-65. The perimeter is ...
P = 2(L+W)
860 = 2((2w -65) +w)
430 = 3w -65 . . . . . . . . divide by 2, simplify
495 = 3w . . . . . . . . . add 65
w = 165 . . . . . . . . divide by 3
2w -65 = 330 -65 = 265 . . . . . find the length
The base is 265 ft long and 165 ft wide.