the answer is -$97 for sure. 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 |7 L' ^1 T1 D# z
Think about it this way : A2 |# s: l7 U# o Z
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)5.39.217.77:8898. {/ f8 Y9 `, G+ V3 o
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 |