Answer:
Sum=24
Mean=8
Explanation:
To find the sum of all the numbers you simply would do 8+7+9.
That is 24.
When finding mean you add up all your numbers then divide by the total number of number (I know that sounds a bit confusing. In this case there are only 3 numbers, so that is the one you will use for dividing)
Your equation would look like this
24
_
3
Once you divide you should get 8 as your mean or average in other terms.