Minden Corporation's records show the following results for its first three years of operations: Year 1 Year 2 Year 3 U.S. source income $ 180,000 $ 350,000 $ 800,000 Foreign source income 92,000 500,000 680,000 Taxable income $ 272,000 $ 850,000 $ 1,480,000 Foreign tax paid $ 17,000 $ 52,000 $ 81,600 In year 4, Minden generated $2 million taxable income ($900,000 of which was foreign source) and paid $370,000 foreign income tax. Assume Minden's foreign source income does not qualify as FDII. a. Compute Minden's U.S. tax for years 1, 2, and 3. b. Compute Minden's U.S. tax for year 4. c. Compute the refund generated by the carryback of the year 4 excess radit