the answer is -$97 for sure.
6 X! V* f, ~+ A3 J' E: i3 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 tvb now,tvbnow,bttvb" ]1 M3 I. H+ p# L% t
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
" ^! F# m3 H2 C# D7 j) b2) 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 |