the answer is -$97 for sure.
# ~8 b& ^ K" a- r) |Think about it this way 4 M% `$ c8 m$ \
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)www2.tvboxnow.com+ c, w; N! N2 j( U3 _2 X. I
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 |