First you need to find the slope.
You do this by adding x to both sides to get 3y=x-12
Then, you divide by three on both sides to get y=1/3x -4
to find the new y intercept you insert the point and the slope in the equation
2=1/3(18)+b
You multiply 1/3 and 18 to get 2=6+b
Finally you subtract 6 on both sides to get -4=b.
This means that the equation of the line is the same as the given line