Hi can you please help me find the answer for question a?

During 19 weeks at the height of an inuenza outbreak, the rate at which the number of cases of infection changed could be approximated by |'(t) = - 6.36t + 142.9, where l is the total number of infected people and t is time measured in weeks. Answer parts a) through d). 3) Estimate |(t), the total number of people who have contracted inuenza by time t. Assume that |(0) = 1415. lit) =