( 10 pts) 4 . The population of Smithville was 20,000 in 1980. In 2020, it was 42,000. a. Assuming linear growth, write an equation for the Population, P(t), as a function of time, t, SINCE 1980 20 0600 b. Assuming the trend continues , what will the population be in 2030? c. In what year was the population 36,000