3y+21+8y
11y+21 is the answer
As, synthetic division by -4 gives remainder 0. Hence, Option B is correct. -4 is a root of 
As, x+4=0 gives x=-4.
So, option C is correct,
(x+4) is factor of 
Option E is correct

The volume of the rectangular prism is equal to length times width times height. Since length and width are equal, the formula includes the squaring of the length. after substitution, the formula is 9^2 * 5 equal to 405 m^3.
So the answer is D. 405 cubic meters