The square base area is 6 x 6 = 36. Then each triangle is the same base and height. Formula for area is 1/2(b)(h). So, each triangle is 1/2(6)(12)=36. So all sides are 36x5=180 units squared.
x^2 - x - 2 is the answer
N+2n+20-4=12+3n
3n+20-4-12=12-12+3n
3n+4=3n
3n/3 + 4= 3n/3
n+4=n
n+4-4=n-4
n=n-4
theres no further simplification, unless i messed up ...
Recall that the derivative of a constant is 0.