To use the substitution method, we should take one of the equations, and obtain an expression for one of the variables from this equation. Let's take the first one: 3x-2y = 11. We obtain an expression for x (it could be for y as well): 3x = 11 + 2 y ⇒ .
Now, we should replace the expression obtain for x in the first equation, on the second equation, as follow
⇒
Then rearranging terms
This expression results in
Finally, using the firs equation, in which we obtained an expression from x, , we replace y=1/2 and get , then