Respostas

2014-02-28T19:00:10-03:00
3x+20+7x=90 
3x + 7x = 90 - 20
10x = 70
x = 70 / 10
x = 7
1 5 1
2014-02-28T19:08:46-03:00
3x+20+7x=90
10x+20=90
10x=90-20
10x=70
x=70\10
x= 7