Elimination is the best way since there are no terms that are just 
x, -x, y, or -y.

To make the x terms cancel out, multiply the first equation through
by -2. Then the 2x will become -4x and will cancel when we add the
two equations term by term:



Now we add them term by term we get



When the first letter comes out to a fraction, instead of substituting it, it is
often easier to start all over and eliminate the other letter y.  I will do that
to illustrate, even though substituting that fraction would be easy.



To make the y terms cancel out, multiply the second equation through
by 4. Then the -3y will become -12y and will cancel when we add the
two equations term by term:



Now we add them term by term we get





Edwin