Solving two linear equations with two variables - substitution method

We have two linear equation:

x   + 3y = 17
3x + 2y = 23

We substitute x = 17 - 3y in the second equation and we have:

3(17 - 3y) + 2y = 23

51 - 9y + 2y = 23

7y = 28

y = 4

Now we find  x:

x = 17 - 3y = 17 - 3*4 = 17 - 12 = 5

x = 5