the answer is -$97 for sure. 公仔箱論壇+ a9 x% t7 z$ i C( ~1 p
Think about it this way ) x- N# R* J3 z Q& P+ c
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
% @$ @2 J: A& }. a" K5 n0 {5 `tvb now,tvbnow,bttvb2) 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 |