the answer is -$97 for sure.
. v/ T5 I2 t+ jTVBNOW 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 2 L. s. ?8 [( {/ l
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18). J" I' }) Z/ }& L
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 |