In 1985, there was 285 cell phones subscribers in the small town of centerville. after 1985, the number of subscribers increased by 75% per year. how many cell phones subscribers were in centerville in 1994 ?

First we write a function that suits the problem.
 We have then:
 y = 285 * (1.75) ^ x
 Then, we see how many years there are in the requested period
 x = 1994-1985 = 9
 We evaluate the function for x = 9
 y = 285 * (1.75) ^ 9
 y = 43871.98637
 Round nearest whole number
 y = 43872
 
 there were 43872 cell phones subscribers in centerville in 1994