回复：回复：回复：how many left?

来源: jinjing 于 2010-01-13 18:23:15 [] [旧帖] [给我悄悄话] 阅读数 : (160 bytes)
回答: 回复：how many left? 由 Jinjing 于 2010-01-12 19:36:51

I think you are smart enough to know how did I get 6. it is wrong:
(30-4x)+15-x=15. x=6 .there are 15 are on 6th mile.15-9=6.
intuition sometime is wrong.

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