Several political leaders, including some past presidential candidates, have proposed a flat income tax, where the marginal tax rate is constant. As of 2009, 24 countries-including 20 formerly centrally planned economies of Central and Eastern Europe and Eurasia-switched to a flat personal income tax rate (Duncan and Peter, 2009). Show that if each person is allowed a "personal deduction" where the first $10,000 earned by the person is untaxed, the flat tax can be a progressive tax in which rich people pay a higher average tax rate than poor people?