the answer is -$97 for sure. % C' Q/ T6 F( _/ {* i: h" Q2 f0 @; PThink about it this way 5.39.217.76; w% Y% h5 r$ B0 ^+ _
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18) $ F2 N8 c7 P: z公仔箱論壇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