3y=3x-6
9=8x-9y
In standard form,
3y=3x-6...[1]
9y=8x-9...[2]
Plot the first line on a graph,and then plot the second.The point of intersection of the two straight lines is the unique solution of the two equations.
Note:if you solved these two equations using algebra,you would get:
(x=9, y=7}
However,as you are graphing these two points,we get-
[1st line]{Simplifying:y=x-2}
x,y
7,5
9,7
11,9
[2nd line]{Simplifying:y=(9-8x)/-9}
x,y
7,47/9
9,7
11,79/9
Since this might not be all that clear,I am including the graph as well.
It should look something like this:

As you can see from the above graph,the point of intersection is (9,7) and hence this is the solution for the given pair of equations.
Prabhat.