Question 83635
first equation: slope=(5-3)/(5-3)=2/2=1. 
3=1*3+b, 3=3+b, b=3-3, b=0.
thus we have the line equation y=x (red line-m) (intersect=0,0)
second equation:slope=(-3-3)/(5-3)=-6/2=-3.
-3=-3*3+b, -3=-9+b. -3+9=b. b=6. 
thus we have the line equation y=-3x+6 (green line-n) (intersect=2,6)
{{{ graph( 300, 300, -6, 5, -10, 10, y = x, y = -3x +6) }}} (graph 300x300 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = x and y = -3x +6). 
y=x now substitute in the second equation
x=-3x+6
x+3x=6
4x=6
x=6/4
x=3/2 answer.
y=3/2 answer.