the answer is -$97 for sure. 0 d% L! I3 }4 \# W( n: n. x+ O
Think about it this way
7 X9 N, v& H* E! K6 m1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)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。9 X: L, c! P# }+ t
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 |