prozzy

the answer is -$97 for sure.
: U+ t0 y# `7 m0 }7 }tvb now,tvbnow,bttvbThink about it this way
# i! L6 d! L" y! a6 K- t0 a1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)
' ^( V5 X. ~+ N/ atvb 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