The substitution method is the algebraic method to solve simultaneous linear equations. Take the expression you got for the variable in step 1 and plug it substitute it using parentheses into the other equation. In the other equation substitute for the variable just solved.
It does not matter which equation or which variable you pick.
And then on the right-hand side you get x is equal to 11 plus y or y plus 11. Use the method of substitution to solve the system of linear equations below. The answer will be the same regardless. Check the solution in both original equations.