In 2015, Skylar sold an apartment building for $20,000 cash and a $300,000 note due in two years. Skylar's cost of the property was $250,000, and he had deducted depreciation of $150,000, $60,000 of which was in excess of what the straight-line amount would have been.

a. Under the installment sales method, what is Skylar's total realized gain?

b. In 2015, how much § 1250 gain does Skylar recognize? How much § 1231 gain does he recognize?