the answer is -$97 for sure.
: q9 O! h5 ^9 |1 f% w. x, M( @2 N公仔箱論壇Think about it this way 公仔箱論壇. B( s" G! A. ` n4 b) Q
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
+ v. P. \3 Y+ A公仔箱論壇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 |