Respostas

2014-07-27T16:01:29-03:00
7y+5-y+8 = 31
7y-y+5+8-31 = 0
6y+13-31 = 0
6y-18 = 0
y= -18/6
y= -3
2014-07-27T16:02:18-03:00
6y+13=31
6y=31-13
6y=18
y=18/6
y=3