Find the length of one side.
V = s^3
s = cube root of V
V = 729
s = cube root 729
s = 9
Put this into your calculator as 729^0.333333333
It should bring back 9 or 8.999999 something which means 9.
Net
The net is shown below. You will have to do the labeling. But I can tell you what you should label each face as?
Area of one face = s^2
s = 9
Area of one face = 9*9
Area of one face = 81
So when you draw this, each face should be labeled with 81.
It should have it's units (ft^2) if your marker is picky.
Part C
There are 6 sides.
1 side has an area of 81 ft^2
6 sides have an area of 6*81 = 486 ft^2

Round to whichever place is needed
20+2N=52
now subtract 20 from each side, to get 2N alone
2N=32
now divide each side by 2
N=16
By definition of conditional probability,
P(B | A) = P(A ∩ B)/P(A) = (13/25) / (13/20) = 20/25 = 4/5