The discovery of one case of bovine spongiform encephalopathy, or mad cow disease, in May 2003 in Canada led to an immediate ban on all Canadian beef exports. At the beginning of September 2003, the ban was lifted, and exports of Canadian beef rose at a steady rate of $42.5 million per month. Express the value of the monthly exports of Canadian beef as a function of time for the period starting the first day of September 2003. What was the value of the monthly exports at the end of December 2003, when presumably the exports regained their normal level?