y - 1 = 1/2(x - 2)
y - 1 = 1/2x - 1
y = 1/2x
2x + 1 = 1/2x...multiply by 2
4x + 2 = x
4x - x = -2
3x = -2
x = -2/3
y = 1/2x
y = 1/2(-2/3)
y = -2/6 which reduces to -1/3
so ur solution is (-2/3,-1/3)
Quadrant III contains (-x,-y).....so ur solution lays in quadrant III