A cellular company purchased $25,700 in cell phones on April 25. The terms of sale were 4/20, 3/30, n/60. Freight terms were F.O.B. destination. Returned goods amounted to $650. (a) What is the net amount due (in $) if the cellular company sends the manufacturer a partial payment of $4,000 on May 20? (Round your answer to the nearest cent.)