me assume yu meen the point=(-5,5) & line 1 be y=-5x+konst
it hav slope=-5, so line at 90 deg tuit hav slope=+1/5...or 0.2
thus perpend line be y=-0.2x+konst
tu make this go thru (-5,5), y gotta =5 at x=-5
so, 5=-0.2*(-5)+konst
5=+1-5+konst...become konst=5+5-1...10-1..9