Respostas

2014-02-04T13:07:16-02:00
(x.-3)+500=20
-3x+500=20
-3x=20-500
-3x=-480        (-1)
3x=480
x=480/3
x=160
2014-02-04T13:07:58-02:00
X . (-3) + 500 = 20
-3x = - 500 + 20
-3x = -480
(-1)  - 3x = - 480
3x = 480
x= 480/3
x= 160