Daily crude oil production by Pemex, Mexico's national oil company, for 2008-2013 could be approximated by P(t) = 0.017t^2 - 0.4t + 5.23 million barrels (8 ≤ t ≤ 13), where t is time in years since the start of 2000. Find the derivative function dP/dt. dP/dt = ? At what rate was oil production changing at the start of 2010 (t = 10)? Daily oil production was decreasing at a rate of ? million barrels per year.