Respostas

2013-11-06T07:51:34-02:00
3x-3-7 = 15
3x = 15 +3 +7
3x= 25 
x = 25/3 

2013-11-06T09:59:13-02:00
3 (x - 1) - 7 = 15
3x - 3 - 7 = 15
3x = 15 + 7 + 3
3x = 25
x = 25/3
x = 8,3333