Could i please get some help with this? It would mean a lot, thank you!

Question 1: The approximate rate of change in the number (in billions) of monthly text messages is given by f'(t) =7.50t -16.8 where t represents the number of years since 2000. In 2005 (t = 5) there were approximately 9.8 billion monthly text messages. [Source: Cellular Telecommunication & Internet Association] a) Find the function that gives the total number (in billions) of monthly text messages in year t. b) According to this function, how many monthly text messages were there in 2009? Compare this with the actual number of 152.7 billion. [Source: Modified from "Calculus for the Life Sciences" by Greenwell, Ritchey, Lial. 2nd ed. 2015]