prozzy

the answer is -$97 for sure.
8 o8 K" n3 f( [& T. KTVBNOW 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 os.tvboxnow.com6 |7 K/ {3 y4 a3 I7 |- T: P6 d
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
% P  \) J- ^4 t/ eTVBNOW 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。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