Respostas

2012-12-12T22:41:49-02:00

2r - 3r - 9 = 8r - 12

-r - 9 = 8r - 12

-r - 8r = - 12 + 9

- 9r = -3 *(-1)

9r = 3

r = 3/9

r = 1/3

1 1 1