the answer is -$97 for sure.
7 m( F4 U7 e7 Q' L1 t% h/ 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。Think about it this way
K4 R! t3 |* ^7 n1 z8 ytvb now,tvbnow,bttvb1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)tvb now,tvbnow,bttvb2 K E7 I/ p2 \- B. C
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 |