Answer
Infinitely many solutions
Work Step by Step
Simplify 9x - 3y = 12
$\frac{9x - 3y}{3}$ = $\frac{12}{3}$
3x - y = 4
y = 3x - 4
This is equal to the other equation y = 3x - 4
Any solution on y = 3x - 4 would satisfy 9x - 3y = 12, and vice versa
Therefore this system has infinitely many solutions