Robert has been an active postage-stamp collector for a number of years. A few years ago, he bought a rare U.S. postage stamp for $2800 . He has now decided to sell the stamp. If he sells it at an aucction and receives $3150 but pays a 20% sales commission on the amount received, what will be Robert's capital gain or loss?
◯ $280
◯ $70
◯ $280
◯ $350
