Walt and Deloris, who file a joint return, have two dependent children, Bill and Tiffany. Bill is a freshman at State University and Tiffany is working on her graduate degree. The couple paid qualified expenses of $2,700 for Bill (who is a half-time student) and $6,600 for Tiffany. (Do not round intermediate calculations. Round your final answers to the nearest whole dollar amount.) a. What educational tax credits are available if Walt and Deloris report modified AGI of $113,800? b. What educational tax credits are available if Walt and Deloris report modified AGI of $113,800 and Tiffany is taking one class a semester (is less than a half-time student) and not taking classes in a degree program?