strate line tween 2 points: (-6,3) & (2,-5) . . . deltax=2-(-6)=8, deltay=(-5)-3=-8 . . . slope=deltay/deltax=-8/8=-1 . . . y=-1y+konst . . . projekt line from x=-6 tu x=0...deltax=+6 . . . deltay=slope*deltax=-1*(+6)=-6 . . . y=3-6=-3 . . . equashun...y=-y-3