Consider the Following Income Tax Schedule for a Married Couple

Consider the following income tax schedule for a married couple who are combining their incomes and filing jointly: (A)What is the tax owed by the couple if each partner earns $20,000?
(B)Compare the tax that the couple would pay if they were not married (filing as single)with the amount of tax they pay as a married couple (filing jointly).
(C)What is the tax owed by a couple in which one spouse earns $40,000 and the other spouse earns no income?