the answer is -$97 for sure.
0 I) d2 }" ]; a }5 VThink about it this way . p2 ~9 i# P# m) w
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)! u0 O. w. b6 F& X
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 |