strate line thru 2 points: (-9, 6) & (-5, -4)
deltax=-5 -(-9)=4
deltay=-4 -6=-10
slope=deltay/ deltax=-10/4 =-2.5
y=-2.5x +konst
projekt line from x=-5 tu x=0...this deltax=+5
deltay=slope*deltax=-2.5*5=-12.5.
y=-4+(-12.5)=-16.5
formula...y=-2.5x -16.5