the answer is -$97 for sure. 公仔箱論壇: F# g x- v& V" t( C7 S
Think about it this way
, |( E& F) A% ? M2 W- {5 z2 Nwww.tvboxnow.com1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)公仔箱論壇( E( Q" h7 T# b3 X) q0 m2 y
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 |