At 4pm the temperature started to change drastically. each hour for three hours, the temperature decreases by 7 . which expression best shows another way to write the product for the temperature

7+7+7

7+7+7+7

(-1)(7+7+7)

(-7)+(-7)+(-7)+(-7)

First off, because the temperature is decreasing, that means the final answer would be negative, or we can also say that there would be a -1 to be multiplied by the change. 

Each hour temperature changes by 7. The question also says that temperature keeps on changing for 3 hours. Therefore the temperature change would be by 3 7's, or 7+7+7.

Lastly, add the -1 from the beginning since it is a negative temperature change, the answer is (-1)(7+7+7)