Daily oil imports to the US. from Mexico can be approximated by: q (t) = 39t2 + 800t 3000 in thousand barrels Where t is the time in years since the start of 2000. At the start of 2010, the price of oil was $105 per barrel and increasing at a rate of $70 per year. How fast was (daily) oil expenditures for imports from Mexico changing at that time