From 2.00PM to 9.00PM the temperature dropped 2.5 degrees per hour.
This is a 7-hour span, so the temperature dropped a total of
[tex] 2.5 \times 7 = 17.5^\circ[/tex]
Then, the temerature dropped another 9 degrees, for a total of
[tex] 17.5+9 = 26.5^\circ[/tex]
