Under a 2017 divorce agreement, Elise Cumber is required to pay her ex-husband, Charles, $1,500 per month until their son aged 16, is 18 years old at which time the amount is reduced to $600.

a). How much of that amount may be deducted by Elise?

b). How much of the monthly payment may be included in Charles taxable income?

c). How much would be the deductible/included if the divorce agreement were dated 2019?