You can put this solution on YOUR website! If the rectangle is roped off, that's the perimeter. The perimeter is twice the length plus twice the width. You're already given the length as 65.
P = 2L + 2W
200 = 2(65) + 2W
200 = 130 + 2W
70 = 2W
35 = W
Now you have both the length and the width. Multiply the length by the width to get the area.
65 * 35 = 2275 sq m