回複：回複：回複：how many left?

來源: 於 2010-01-13 18:23:15 [舊帖] [給我悄悄話] 本文已被閱讀：次

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.