strate line from 5x+20y=10, or y=(10-5x)/20
is av form y=-(5/20)x or (1/4)x, thus slope=1/4
then get line av form y=0.25x+konst that go thru point=(8,3)
projekt line from point til x=0...deltax=-8, so deltay=-8/4=-2
thus, y-intersept=3-2=1
formula: y=0.25x+1