Joan and Harry Leahy both had income in 2015. Harry made $72,500 in wages. Joan has an incorporated small business that paid her a salary of $50,000. In addition, the business had profits of $15,000, which were paid to the Leahys as dividends. They received $5,600 in interest on savings and $350 in interest on a loan made to Harry's brother Lou. Lou also repaid $2,000 of principal on that loan during the year. The couple had interest income from two bonds, $2,200 on a 20-year IBM issue, and $2,700 on a State of Michigan revenue bond.

They sold some Biotech stock for $14,000 that had been purchased five years before for $4,000. Two years ago they invested $50,000 in some rural land on the advice of a real estate agent. They sold the property in 2015 for $46,000.

The Leahys paid $12,500 in mortgage payments of which $9,000 was interest and the rest reduced principal. They paid real estate taxes of $2,750 and state income tax of $6,800 during the year. They contributed $1,500 to their church and $3,000 to the support of Joan's elderly mother. They have two young children. (Joan's mother is not a dependent.)

a. Calculate the Leahy's taxable income.

b. What is their tax liability for 2015?

c. What is their average tax rate?

d. What is their marginal tax rate? Can there be more than one marginal rate? Explain.