At the end of 2008, the price of a gallon of milk was $3.68. What was the price, in dollars, of a gallon of milk at the end of 2013?

On a certain fall day in Anchorage, Alaska, the temperature at 1:00 a. m. was 21.6°C. At 1:00 p. m. (12 hours later), the temperature had risen to 3.2°C. On average, how much did the temperature change, in degrees, each hour from 1:00 a. m. to 1:00 p. m.?

21.6° per hour

20.4° per hour

0.4° per hour

1.6° per hour

Please show your work.