原帖由 prozzy 於 2007-5-18 23:05 發表。 
9 _' _% W! e1 y+ ~! O3 a2 Dtvb now,tvbnow,bttvbthe answer is -$97 for sure.
" B/ t" e4 H9 |: l R2 X# z公仔箱論壇Think about it this way
5 L/ z( Q2 @& n; g1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)& B' _4 O! f8 F
2) Now, the owner discovered that the 100 bucks is fake. You can th ... 5 C, i8 j) |/ l# C. E. y1 Cos.tvboxnow.com' [& b9 w2 `% H5 Q* y- I' c
os.tvboxnow.com# w+ d+ y# D' _8 p
1) very good, it the 100 bucks is real, your answer is correct, but it is fake, so your answer is wrong
% E5 x7 q& d: n, i! W公仔箱論壇 ' [; l" u8 h: Y5 t+ ~
think about it, when the bill is fake, and he gave him $79 change back, that is -79 already, it means the 100 on his hand is equal to 0 (Zero), how did he makes profit when he got a fake bills, then he need to pay another real 100 dollars bill to his neighbor, that another -100, plus the product he lost, thats another 18 dollars, Do Not Even Mention the 3 dollars, there is no profit he can make when he got a fake bill.
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( y' r- [0 u0 MI know the answer becoz it really happening to my friend in his store in real LIFE, it can not be wrong. |