Determine the taxable amount of Social Security benefits for the following situations. If required, round your answers to the nearest dollar. If an amount is zero, enter "0".

a. Erwin and Eleanor are married and file a joint tax return. They have an adjusted gross income of $39,200, no tax-exempt interest, and $13,720 of Social Security benefits. As a result, $ of the Social Security benefits are taxable.

b. Assume Erwin and Eleanor have adjusted gross income of $18,800, no tax-exempt interest, and $20,680 of Social Security benefits. As a result, $ of the Social Security benefits are taxable.

c. Assume Erwin and Eleanor have adjusted gross income of $106,000, no tax-exempt interest, and $15,900 of Social Security benefits. As a result, $ of the Social Security benefits are taxable.