The linear equation of a line can be expressed as,
y=mx+c
Here, m is the slope of the line and c is the y intercept.
Comparing equations y=3x+2 and y=3x-6 with y=mx+c we find that the slope of the lines expressed by the equations is same and is equal to m=3.
If two lines have the same slope, then the lines are parallel to each other.
Two parallel lines will never intersect. Therefore, the system of equations y=3x+2 and y=3x-6 have no solution.