the answer is -$97 for sure.
$ ^, P3 m3 T k7 f公仔箱論壇Think about it this way
, Z' y* r0 Y& c( T) y' r$ _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。1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)tvb now,tvbnow,bttvb, C; w) C* {" {0 d! }( u4 I
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 |