It's pretty simple once you understand how to do it. First we have to find the change in the time. Since it started at 10:00 and went to 15:00 (military time is useful in these problems) the time has changed a total of 5 hours. And since this temperature increases 2.25 degrees each hour, we would multiply 2.25 by 5 which gets us 11.25. Then all we have to do next is add 11.25 and -3 which gets us 8.25 degrees as the answer.
