the answer is -$97 for sure. 公仔箱論壇1 I1 V- h6 a. y n) e- D
Think about it this way 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。8 l a) d f# u4 f1 \) [7 A4 ]
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
# O& V! n+ h4 nTVBNOW 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 |