Respuesta :

5 + r - 2 = 9     add 2 to both sides (because they are like terms)
        + 2 +2
5 + r = 11        subtract 5 from both sides, 5-5 cancels out and 11 - 5 is 6
-5       -5
r = 6
6 because 5+6=11-2=9