Ripped from the headlines volume 1-12 from the Florida-times union: 3/18/2013 AP calculus bc homework

The price of gas in Portland, Maine for the month of April is modeled by the function P, where P(:) is measured in cents and / is measured in days for Or $ 30. The rate at which the price of a gallon of regular gasoline is changing is given by P'() =7.8sin(0.06:)-6.8. The price of a gallon of regular on April 1 is $3.50. inc ? *a) Find the day ? (if it exists) , 0 /