Consider John, a 68 year old individual facing a 39.6% marginal tax rate, with no wage income. Assume that if he earns a dollar, he loses 50 cents in Social Security benefits, and that 85% of his Social Security benefits are included in taxable income.

a) Calculate his total marginal tax rate

b) If he lives in California and faces an 11% state income tax, what is his marginal rate?