Slope is rise over run, or y over x. Firstx subtract your y values. Make sure that whichever way you want to subtract them (whether you use 2 - 6 or 6 - 2) that you do the same to the x values. So, 2 - 2 is 0. Now, you could go ahead and do the rest of the equation, but there's really no need. A 0 as the numerator means there's no slope, or zero slope.
