20x+50y=800 you can turn it into slope-intercept form and it would end up being y=-2/3x+16 so now you have your y intercept (16) and you know your rise and run -2(rise)3(run).
Or you can substitute a zero for x and solve for y
20(0)+50y=800 which equals 50y=800 which equals 16 y=16
then you substitute a zero for y and solve for x
20x+50(0)=800 which equals 20x=800 which equals 40 x=40
