Mr. wolf purchased a building in year 1 to use in his business. the purchase price was $400,000. he paid $100,000 cash and took out a mortgage of $300,000. in year 11, he made certain permanent improvements to the building at a cost of $80,000. in year 20, mr. wolf sold the building for $600,000 in cash and relief from the remaining mortgage balance of $100,000. by the time of sale, mr. wolf had repaid a total of $200,000 principal on the original $300,000 mortgage and had deducted $180,000 total depreciation on the original cost and improvements. what is mr. wolf's realized gain on the sale?