the answer is -$97 for sure.
1 j% I1 n: {5 qTVBNOW 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
* l7 Q% Q& y# g {" p( Z& `公仔箱論壇1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18), B8 ?. H+ e+ L& U1 p& f
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 |