Math question about graphing

Using this form ax+by=C ,

would the the equation be ... 2/3x +y = 4

with the plots (3,2) (-3,6)

start with y=mx+b
m=slope=-2/3
x=3 or -3
b=2 or 6

2/3x+y=2
or
2/3x+y=6
do not subtract the y coordinates