You need to use substitution, to do so, you isolate one of the variables x or y in one equation, and then you substitute that equation into the other.
Since you only need to find x, isolate the y in one of the equations
x - 2y = 4
y = [tex]\frac{x}{2} -2[/tex]
Plug this in and simplify
9x + 2y = 16
9x + 2([tex]\frac{x}{2} -2[/tex]) = 16 Distribute the 2
9x + x - 4 = 16
10x = 20
x = 2 Your answer is C
