=(3x+6)^3
= 27x^3+216
The last term is 216.

To solve the given system of equations for substitution you:
1. Solve in one of the equations a variable.
For the given options the one that is correct is solve the first equation for y, by adding x to both sides:
4x + 2y = 27.50
4(5.75) + 2y = 27.50
23 + 2y = 27.50
2y = 4.50
y = 2.25 I think ?
The answer is C because if you do 7 divided by 25 your answer is 0.28