Quick Print Press borrowed $$20,000$ from the Provincial Bank on May $25$ at $7\mathrm{.}5\%$ and secured the loan by signing a promissory note subject to a variable rate of interest. Quick Print made partial payments of $$5000$ on July $10$ and $$8000$ on September $15.$ The rate of interest was increased to $8\%$ effective August $1$ and to $8\mathrm{.}5\%$ effective October $1.$ What payment must Quick Print make on October $31$ if$,$ under the terms of the loan agreement, any interest accrued as of October $31$ is to be paid on October $31?$

Quick Print must make a payment of $ $q,$ on October $31.$

$($Round to the nearest cent as needed.$)$