Question

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)

Answer 1

The answer would be (-1) (7)(7)(7) because whenever -1 is multiplied by a number, it results in the opposite.
The rule for integer multiplication is: same sign times same sign = positive
different sign times different sign= negative
 
Since the key word is decreases, we know it is a negative times positive= negative. So any answer that does not have a negative answer will be eliminated. 

To make it easy, all the other options are positive. So, that leaves you with the 3rd option.  

Answer 2

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)