Shawn Bixby borrowed $23,000 on a 180-day, 11% note. After 80 days, Shawn paid $2,600 on the note. On day 120, Shawn paid an additional $4,600. 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.)

a. Total interest $_____

b. Determine the ending balance due use the U.S. Rule. (Do not round intermediate calculations. Round your answer to the nearest cent.)