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 higher education expenses and interest on higher-education loans under the following circumstances:

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 $79,000.

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