the answer is -$97 for sure. 公仔箱論壇# h9 e; _: N( o `* W
Think about it this way " A$ c5 w6 z, ~# i. ?& d& `$ K
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)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 K- p, b9 e5 X) t
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 |