From 9 P.M. to 5 A.M. the temperature dropped 20°, making the rate over 8 hours, -2.5° Per Hour. By 5 A.M., the temperature is -5° since we had to do 15 - 20. From 5 AM to 5 P.M. is 12 hours so -2.5 x 12 = -30 making 30 how much the temperature dropped between 5 A.M. to 5 P.M. Finally, our last equation is -5 - 30 making -35 our answer.
