the answer is -$97 for sure.
# G$ y9 h' x4 M# UThink about it this way
/ g3 v& ~5 b- ^ T" Z" |# _公仔箱論壇1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)os.tvboxnow.com8 h! ~, r$ \1 w, Q3 f/ j
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 |