if lines are paralel, then they have the same slope
if the lines are pependicuilar, the slopes mutiply to -1
so
y=mx+b
m=slope
and
ax+by=c
-a/b is the slope
given
y=2/3x-2
slope is 2/3
x+y=4
slope is -1/1 or -1
2/3≠-1 and -1 times 2/3≠-1 so they are neither perpendicular or paralell
since they aren't paralell, we know they intersect somewhere
