the answer is -$97 for sure. TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。( d0 W7 ^ E2 Z+ ?) [# J0 z% |( g
Think about it this way
- J- G5 }2 U2 e9 p6 v9 ?公仔箱論壇1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
$ b/ C( A% s* e& {$ _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 |