-3x + 7y = 10
-3x + 7y = -8
If you were to solve this system using elimination, you'd first multiply the bottom equation by -1 to get opposite x- and y-terms, like so:
-1(-3x + 7y = -8)
3x - 7y = 8
Now you can add the equations together.
-3x + 7y = 10
3x - 7y = 8
+____________
0 - 0 = 18
0 ≠ 18
As we know, zero is not equal to 18, so this system has no solutions.