4. Consider a model in which individuals live for two periods and have utility functions of the form U = In(C;) + In(C;). They earn an income of $500 in the first period and no income in the second period. They save S to finance consumption in the second period. The interest rate, r, 1s 5%. (2 points) a. Write the individuals lifetime budget constramnt in terms of Cyand C; (1 point) b. The government is considering imposing either a tax on labor income or a tax on consumption. What 1s the tax rate on consumption that would be economically equivalent to a 20% tax on labor income? (1 point)