21. Martha McDonald purchased an office building in 2001 for $630,000. In 2021, she sells the building for $950,000. Over the years, she had replaced the windows and doors at a cost of $60,000, repainted the exterior at a cost of $15,000, and installed an elevator at a cost of $90,000. Martha had taken straight line depreciation on the building for 20 years, for a total of $400,000.
    1. What is Marthas basis in the building at the time of the sale?
    2. What is her realized gain?
    3. What is her recognized gain?