The population of the surrounding county

A that the population from 1990 to 1998 of the only in a can be modeled by the formula 102t² 225t+ 3090 wheret= 0 represents the year 1990 and that over the same years, the population of the (not including the town) can be modeled by the formula 125t²+ 72t+ 4978 wheret= 0 represents the year 1990. Find a model for the of the county during the years 1990 to 1997.