A town's population has been growing linearly. In 2004 the population was 6,200. By 2009 the population had grown to 8,100. Assume this trend continues. a. Find a linear model to represent the population P of the town as a function of x, the number of years after 2004. b. Assuming that the model continues, predict the population in 2013. a. Assuming that the model continues, identify the year in which the population will reach 15,000