Answer
Infinitely many solutions or all real numbers
Work Step by Step
For the first equation $3x-3y=6$, the $x$ and $y$ intercepts are found as $(2,0)$ and $(0,-2)$ by substituting $0$ for $y$ and $x$ values in the equation respectively.
Similarly, for the second equation $2x=2y+4$, the $x$ and $y$ intercepts are found as $(2,0)$ and $(0,-2)$ by substituting $0$ for $y$ and $x$ values in the equation respectively.
Now, graph each equation as a line passing through the intercepts. It is observed that graphs of both lines coincides with each other. It indicates that the system has infinitely many solutions.
The graph is as below.