the answer is -$97 for sure. TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。, e7 w$ T0 J7 f+ @- \6 ?6 L8 A
Think about it this way
1 C5 m I3 O; ^, L2 m1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
J; a, U1 O$ z5 G2) 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 |