the answer is -$97 for sure. ; ~% w& X; w% q* V
Think about it this way
+ j# }& I8 D4 w$ M' L0 Stvb now,tvbnow,bttvb1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)6 F% f; P* M9 T# 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 |