the answer is -$97 for sure.
& K! ^; B$ }" P* ?公仔箱論壇Think about it this way
; \3 k0 |: n; F9 @4 {9 D. r公仔箱論壇1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
" ~- D9 x7 z5 ]- ]5.39.217.762) 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 |