Robert sold his ranch which was his principal residence during the current taxable year. At the date of the sale, the ranch had an adjusted basis of $460,000 and was encumbered by a mortgage of $200,000. The buyer paid him $500,000 in cash, agreed to take the title subject to the $200,000 mortgage, and agreed to pay him $100,000 with interest at 6 percent one year from the date of sale. How much is Roberts realized gain on the sale?