Respostas

2013-11-14T10:40:26-02:00
A + c = 37 .(-4)
2a+4c = 118

-4a-4c = -148
2a+4c =   118
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-2a = -38
2a = 38
a = 38/2
a = 19

a+c = 37
19+c = 37
c = 37-19
c = 18

19 amigos e 18 cachorros