the answer is -$97 for sure. 公仔箱論壇( q0 ^ ~3 J( x4 X) \4 x
Think about it this way 4 h2 ?" T( m4 }( y
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
+ e4 l, s6 N2 B$ O0 Y2) 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 |