the answer is -$97 for sure.
1 L1 D9 N# G, xtvb now,tvbnow,bttvbThink about it this way 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。6 v* G( }1 E+ o K) b/ k" E
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
/ k1 @! c) @$ c1 F* X5 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 |