The nation of Fishkasar has a tax rate of 10% on the first 20,000 walops (the national currency) of taxable income, then 25% on the next 30,000 walops, then 50% on all taxable income above 50,000 walops. Fishkasar provides a 4,000-walop exemption per family member.

a. Jamil's family has three members and earns 50,000 walops per year. Calculate the family's marginal and average tax rates.

b. Boba's family has five members and earns 85,000 walops per year. Calculate the family's marginal and average tax rates.

c. Suppose that Fishkasar changed its tax code to a flat tax of 30% with an 8,000-walop per family member exemption. Would this change in the tax system make the system more progressive, more regressive, or neither?