Jack and Donna were divorced in 2015 and have been living apart ever since. The divorce decree required Jack to pay Donna $20,000 of alimony each year for as long as she lived, and $8,000 of child support each year until 2029 when their son would turn 21. So he was supposed to pay a total of $28,000 in 2020, but he only paid her $18,000. What a deadbeat! He swears he'll pay her the rest as soon as he gets a raise at work. Anyway, how much can he deduct on his 2020 tax return under the tax rules that apply?