the answer is -$97 for sure. TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。. l% ?2 Y/ S$ N. {- W8 }
Think about it this way B8 R/ Z7 A; v3 @0 B4 K/ ?2 x
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
% E; ^7 f; J& m( 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 |