the answer is -$97 for sure. 公仔箱論壇' O% S- W% [3 I& T; L( \
Think about it this way tvb now,tvbnow,bttvb. n0 X9 b9 ^8 V
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)os.tvboxnow.com0 b; @ t& C7 W& B2 Z
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 |