Respostas

2014-05-11T22:07:43-03:00
A) -3 = x + 10
X= -3 - 10
X= - 13
B) 7x = -21
X= - 21/7
X= -3
2014-05-11T22:13:22-03:00
-x=10+3
-x=13 (-1)
x=-13
prova: -13+10=-3

outra:
7x=-21
x=-21/7
x=-3