Linda and Don are married and file a joint return. In 2021, they received $12,000 in Social Security benefits, $8,000 in taxable interest, and $37,000 in taxable pension benefits.

a. Determine how much of their Social Security benefits are taxable in 2021.

b. Same facts as in a. except that the taxable pension is only $27,000 and they received $6,000 interest from municipal bonds (rather than taxable interest) and is tax-exempt in 2021