I took the AMC 10 A.
Tip: chill when you can't figure something out. Also, if you are sure you don't know how to solve any of the problems left, then double check your answers for the problems you did do.
x:6 = 5:3 because of parallel lines.
we can write this in fraction form and solve:
I revised it.
if you take the square root of 2^16, the answer is 2^(16/2)=2^8=16^2=256
I think the parallelogram has height 6 and the sides perpendicular to the height are 9, and the two remaining sides that are not parallel to the height are 2.5.
In that case, you use the formula a=bh, so the answer is 9*6=54.
Actually I solved it myself:
since every corner have two extra 20 feet (40 feet)
and there are 4 corners, 4*40 = 160ft