L$0\mathrm{.}1$ Kareem bought a rental house in March $2018$ for $$300,000,$ of which $$50,000$ is allocated to the land and $$250,000$ to the building. Early in $2020,$ he had a tennis court built in the backyard at a cost of $$7,500.$ Kareem has deducted $$30,900$ for depreciation on the house and $$1,300$ for depreciation on the court. In January $2023,$ he sells the house and tennis court for $$330,000$ cash.

a$.$ What is Kareem's realized gain or loss?

b$.$ If an original mortgage of $$80,000$ is still outstanding and the buyer assumes the mortgage in addition to the eash payment, what is Kareem's realized gain or loss?

c$.$ If the buyer takes the property subject to the $$80,000$ mortgage rather than assuming it$,$ what is Kareem's realized gain or loss?