the answer is -$97 for sure. 7 b. U* ^9 w# l# O5 d
Think about it this way
* Z9 R2 z9 n# t4 l8 o公仔箱論壇1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18); J7 M1 I2 F0 u% M) L9 a
2) Now, the owner discovered that the 100 bucks is fake. You can think this as a lost of $100. therefore the overall gain is $3-$100 = -$97 |