x = y + 2

3x + 3y = 12

3(y + 2 ) + 3y = 12

3(y) (3)( + 2 ) + 3y = 12

3y+6+3y=12

6y+6=12

6y+6-6=12-6

6y=6

6y/6=6/6

y=1

x = 1+ 2 =3