Answer:
infinitely many solutions
Step-by-step explanation:
2x + 2y = 18
x + y = 9
multiply Line M equation by -2 to eliminate at least one variable:
2x + 2y = 18
-2x - 2y = -18
use elimination:
2x + 2y = 18
-2x - 2y = -18
__________
0 + 0 = 0
since this statement is true, there are infinitely many solutions.