the answer is -$97 for sure. 公仔箱論壇1 ]% l( c6 |9 }2 Q! T) I. v' q% t% y- w
Think about it this way os.tvboxnow.com( r9 c% Q3 N# g* t: D1 D6 \
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)os.tvboxnow.com0 y8 r* o! k q, O- w p7 ?4 [8 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 |