>>11480463seller (s)
buyer (b)
Seller and buyer put $20 in the box
(s) -$20
(b) -$20
seller sells the box for $30 to buyer
(s) $10
(b) -$50
buyer opens the box to find $40
End values are seller at +$10 buyer at -$10
I've dumbed it down as much as I can, assuming OP isn't trolling how can anyone over the age of 10 not understand this