You don't zonvert it. All you do is take the slope, m, from the first equation, find the y-intercept, b, and input it into the second equation. For example, if your two points are (0,5) and the second point is (5,6), then you would do:
m=(5-6)/(0-5)=-1/-5=1/5.
y-intercept=b=(I made it simple) 5
y=(1/5)x+5
