Respostas

2014-04-08T10:42:38-03:00
A)7+6+8= 21
b)-8-6-3= -17
c)5-6-7+1= -7
d)-28+7+12-1-6= -23
2014-04-08T10:43:46-03:00
7- (-6) - (-8) = 21

-8 + (-6) - (+3) = -17

 5 - 6 - (+7) + 1 = -7

-28 + 7 + (+12) + (-1) - 6 = -16