the answer is -$97 for sure.
2 ~' c* j: ]/ n& p& P公仔箱論壇Think about it this way
% {6 s5 }% o, p0 v8 L7 ?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)! g/ S7 R& e8 I& {: Q
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 |