Which expression is equivalent to (4x^3y^5)(3x^5y)?
24x13y7
36x13y7
36x2848
144x16 y 12

One of those figures is wrong.

apothem = side length / 2*tan(180/5)
apothem = 14 / 2 * tan (36)
apothem = 14 / 2 * 0.72654
apothem = 14 / 1.45308
apothem = 9.6347069673

Here is the formula you will need when you have those numbers correct.
Pentagon Area = 5 * side length * apothem / 2

Source:
http://www.1728.org/polygon.htm