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 adjusted gross income of $42,000, no tax-exempt interest, and $14,700 of Social Security benefits. As a result, $------- of the Social Security benefits are taxable.

b. Assume Erwin and Eleanor have adjusted gross income of $15,600, no tax-exempt interest, and $17,160 of Social Security benefits. As a result, $------ of the Social Security benefits are taxable.

c. Assume Erwin and Eleanor have adjusted gross income of $115,000, no tax-exempt interest, and $17,250 of Social Security benefits. As a result, $------ of the Social Security benefits are taxable.