how many degrees the temperature T fell.
The temperature at 5 P.M. is 20∘F. The temperature at 10 P.M. is −5∘F.
To find out how many degrees the temperature fell, we need to calculate the difference between the two temperatures.
First, let's note the initial temperature at 5 P.M. is 20∘F (let's call it T1), and the final temperature at 10 P.M. is −5∘F (let's call it T2).
To find the difference, we subtract T2 from T1:
20∘F - (-5∘F) = 20∘F + 5∘F = 25∘F
Therefore, the temperature fell by 25 degrees.