the answer is -$97 for sure.
* I: k& a; u7 J7 k+ |tvb now,tvbnow,bttvbThink about it this way
& R/ G" L" N Z( M# o* k' V/ ]公仔箱論壇1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)公仔箱論壇1 c5 J7 k$ [+ 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 |