Respostas

2013-11-23T20:20:20-02:00
20-2(7-5y)+12y
20-14+10y+12y
6+22y
2013-11-23T20:21:30-02:00
20 - 14 +10y+12y = 
22y=14 - 20 
22y=-6
y=-6/22
y=-3/11