If you were to use the substitution method to solve the following system, choose the new equation after the expression equivalent to x from the
second equation is substituted into the first equation

3x + 2y = -21
x - 3y = 4

3(3y + 4) + 2y = -21
3(-3y + 4) + 2y = -21
3x + 2(3y + 4) = -21
3x + 2(-3y + 4) = -21