Answer:
The top system of equations has one solution, the middle system has infinitely many, and the bottom system has no solution.
Explanation:
We can immediately see the top system has one solution because the two equations have different slopes.
For the middle system, we can rearrange terms and multiply by 3 to get that the equations are the same line, so there are infinitely many solutions.
Finally, we can move the -2x to the other side in the first equation of the bottom system to get 2x+y=5. But it also equals -7 from the second equation! This is impossible, so there are no solutions to the bottom system.