When you have linear functions multiplying the differentials like that, what you want to do is have a substitution based on the point of intersection of the two lines (if they are not parallel, as here). So, the left-hand line is x - 1 = 0, and the right-hand line is 3x - 2y - 5 = 0. Obviously, x = 1, and you can find the corresponding y. So let's call the point of intersection You want to do the substitution and The resulting DE will be of a form that you know, I think. What do you get?