You need to know two points on your line, in order to find the slope.
If you're given the y intercept, that is one point, (0,a) where a is the y intercept.
If you're given the x intercept, that's another point, (c,0) where c is the x intercept.
You could also be given points on the line that aren't an x or y intercept. Let's call these points (r,s) and (j,k).
To find the slope of the line, you need just two points. Take the
difference of the y coordinates, and divide by the difference of the x
coordinates to solve for the slope.
Using our two generic points (r,s) and (j,k), we would solve for the slope m as follows:
m = (s-k) ÷ (r-j)
Hope that helped!
