the answer is -$97 for sure. ' ~3 q3 m! I/ Q) g6 y+ i C
Think about it this way
w) x+ S. p$ `9 A& H: |$ ?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。1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)tvb now,tvbnow,bttvb% }( J# r5 J9 O$ h8 R
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 |