Scot and Vidia, married taxpayers, earn $15,000 in taxable income and $5,000 in interest from an investment in City of Tampa bonds. (Use the U.S. tax rate schedule for married filing jointly).

Required:

1. If Scot and Vidia earn an additional $15,000 of taxable income, what is their marginal tax rate on this income?
2. What is their marginal rate if, instead, they report an additional $15,000 in deductions?