Respostas

2014-08-14T17:20:19-03:00
4x - 36 = 0
4x = 36
x = 36/4
x = 9

7x - 21 = 0
7x = 21
x = 21/7
x = 3

x + 9 = 0
x = 9

5x - 20 = 0
5x = 20
x = 20/5
x = 4