The Provincial Bank lent $20 000 to the owner of the Purple Pelican on April 1, 2012, for commercial improvements. The loan was secured by a demand note subject to a variable rate of interest. This rate was 7% on April 1. The rate of interest was raised to 9% effective August 1 and reduced to 8% effective November 1. Partial payments, applied to the loan by the declining balance method, were made as follows: June 10, $1000; September 20, $400; November 15, $1200. How much interest is due to the Provincial Bank on December 31?