Shawn Bixby borrowed $35,000 on a 210-day, 8% note. After 80 days, Shawn paid $3,800 on the note. On day 126, Shawn paid an additional $5,800. Use ordinary interest. a. Determine the total interest use the U.S. Rule. (Do not round intermediate calculations. Round your answer to the nearest cent.) b. Determine the ending balance due use the U.S. Rule. (Do not round intermediate calculations. Round your answer to the nearest cent.)