Respostas

2013-09-24T11:24:41-03:00
4x + 20 + 3x + 15 = 21
7x = 21 - 20 - 15
7x = -14
x = -14/7
x = -2
2013-09-24T11:26:12-03:00
4(x+5)+3(x+5)=21
4x+20+3x+15=21
4x+3x+20+15=21
7x+35=21
7x=21-35
7x=-14
x=-14/7
x=-2