the answer is -$97 for sure.
4 ~, l& @- }, w' r/ v+ FTVBNOW 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。Think about it this way 公仔箱論壇, E& ~! s# q2 B. @+ ]. i9 Q
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
3 u! h0 m, o. z x9 n' _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。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 |