Answer: No solutions
The equations y = 5x+12 and y = 5x+18 are each in the form y = mx+b
We see both have the same slope m = 5, but different y intercepts. Therefore, these equations produce parallel lines. Parallel lines never intersect. Recall that an intersection point is a visual representation of a solution to a system.
The lack of intersection points tells us the system doesn't have any solutions. We consider this system to be inconsistent.