We are given that y = 3 - 2x
We will substitute with this value in the second equation as follows:
-6y + 18 = 12x
-6 (3-2x) + 18 = 12x
-18 + 12x + 18 = 12x
This will give us zero = zero
A 0=0 solution means that the system has infinitely many solutions.
Therefore, the answer is (c)
