Lionel is an unmarried law student at State University Law School, a qualified educational institution. This year Lionel borrowed $$27,000$ from County Bank and paid interest of $$1,620.$ Lionel used the loan proceeds to pay his law school tuition. Calculate the amounts Lionel can deduct for interest on higher$-$education loans under the following circumstances:

Note: Leave no answer blank. Enter zero if applicable.

a$.$ Lionel's AGI before deducting interest on higher$-$education loans is $$50,000.$

b$.$ Lionel's AGI before deducting interest on higher$-$education loans is $$84,000$

c$.$ Lionel's AGI before deducting interest on higher$-$ education loans is $$90,000$