To find the mean, you have to add all the numbers then divide it by how many numbers there are.
In this case, you'll need to add all those numbers and divide it by 4.

The mean is 1995.
C. The Y value does not change because you are only reflecting over x= lines. After the first, it is (-3.5). Then (7, 5)
500 and 100 because if you see the seven right, seven is the judge and so as the one. Make it 500 and the next number 100. So you'll have en estimate of 600. Ur welcome.
There are 4 terms in the expression