the answer is -$97 for sure.
* p, N9 b/ m! D( Vtvb now,tvbnow,bttvbThink about it this way 6 @! v/ J, t) i3 W. k
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)tvb now,tvbnow,bttvb: u) w; S1 f5 n8 u) t4 |% Q4 W
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 |