Answer: No solutions
The system is inconsistent.
The two lines are parallel and never intersect.
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Work Shown:
Solving the 1st equation for y.
3x-y=18
-y=18-3x
y = -(18-3x)
y = -18+3x
y = 3x-18
Plugging that into the other equation to solve for x.
-2y=-6x-120
-2(y)=-6x-120
-2(3x-18)=-6x-120
-6x+36=-6x-120
-6x+6x=-120-36
0x = -156
0 = -156
We arrive at a false statement.
Therefore, this system has no solutions
The system is inconsistent.
If you were to use a graphing tool like Desmos or GeoGebra, then you'll see the two lines are parallel. They never intersect to form a solution.