5. Consider a couple who jointly earn $300,000, have three children ages 10, 15 and 20. They pay $4,000 in child care expenses for the child who is 10, pay $25,000 in college tuition for the other child (who is 20 years old), pay $5,000 in mortgage interest, and pay $22,000 state and local property taxes. Assume they file their tax return jointly. It makes sense to use a spreadsheet to do this problem. Do not use a tax calculator. Read everything below!

Tuition expenses are an allowable above the line deduction

The standard deduction (for married couples filing jointly) is $24,000

There are no personal exemptions

Only $10,000 of state and local property taxes are allowed as an itemized deduction

Mortgage interest is an itemized deduction

For married couples filing jointly, the first $19,050 of taxable income is taxed at 10 percent, taxable income between $19,051 and $77,400 is taxed at 12 percent and taxable income between 77,401 and $165,000 is taxed at 22% and taxable income over $165,000 and under $315,000 is taxed at 24%.

The child credit is $2,000 per child aged 16 or under. For the purpose of this question, the child in college does not qualify for the child credit.

Only $3,000 of child care expenditures are eligible for the child care credit for this family. When a couples adjusted gross income is $15,000 or below, the credit rate is 35 percent if they file jointly. For every extra $2,000 dollars of AGI above $15,000, the credit amount is reduced by 1 percentage point. This means if their AGI is $25,000, the credit rate is 30%. Instead of getting a credit of (.35)$3,000, they get a credit of (.30)$6,000. If AGI is greater than $43,000 the credit rate is 20%

a. What taxes do they owe after credits?

b. What is their marginal tax rate (what happens if they earns an extra dollar)?

c. What is their average tax rate?

Please show how to find each answer, thank you!