Mrs. Kwan withdrew the entire $8,000 balance from her Roth IRA this year. Her total contributions to the account were $6,070, and her marginal tax rate is 15 percent. Determine the tax cost of the withdrawal if:
a. Mrs. Kwan is age 63 and opened the Roth IRA three years ago.
b. Mrs. Kwan is age 63 and opened the Roth IRA seven years ago.
c. Mrs. Kwan is age 48 and opened the Roth IRA seven years ago.