Respostas

2014-06-09T21:46:27-03:00
42 anos.
(x+21) :3 = ×÷2 (em forma de fração)

produto dos meios é igual ao produto dos extremos
2x+42=3x
x=42

tirando a prova
63÷3=42÷2
21=21
2 3 2
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