3y-x+3=0
divide by 3
y-x+1=0
multiply by -1 and put it into standard form
x-y-1=0
y=-2x+6
Set it equal to 0 and put it into standard form
2x+y-6=0
Now you can solve by substitution.
x-y-1=0
+2x+y-6=0
-----------------
3x-7=0
3x=7
x=7/3
Substitute it into the equation above:
7/3-y-1=0
4/3-y=0
4/3=y
x=7/3 or 2 1/3 y=4/3 or 1 1/3 (7/3,4/3)
Hope that helps
