If you are trying to find where they intercept the axis you are on the right track... No need to graph though.
These two equations represent two different lines. They will intersect at different points.
Let's use what you have written already and find the x intercept. What is the value of y at the x axis?
So, set y to 0 in your equation and you will have the x-intercept. Now do the same but setting x to 0 so you will find the y-intercept.
Is this what you are after?