rise over run equation is y2-y1/x2-x1
(5,0) (1,2)
2-0/1-5
2/-4
so -2/4
simplified would be -1/2
Depending on if you need to simplify it or not it will be negative 2/4 (-2/4) or negative 1/2 (-1/2).
Even if you switch the numbers around to make is 0-2/5-1 it would still come out to be -2/4