X=2 is the answer for this question.
I would substitute y = x^2
4y^2 -21y+20=0
C=2pir, so take half of 15 which is 7.5 and plug it in as r and you get 47.12. Or just look up circumference calculator on google.
The volume of the pyramid is 448m^3
(16)(12)(7)/3
= 1334/3
= 448
