Just checking I'm not going crazy:

Find the point of intersection of the lines . I have tried to deduce by saying that where the lines intersect, their y values will be identical, and so the difference of the two must equal 0:

Therefore,

I can obviously plug x into one of the above equations to get the y value for the intersection. Is correct? The answer in my book gives the reciprocal of this, but I have gone over solving the equation -7x + 8 several times and I still get the same result.