AS Mathematics S1 mean, variance and standard deviation for coded data

This is the question:
A mathematics student has been asked to calculate some properties of the volumes, x cm^3, of a sample of 8 solid objects. To make the calculations easier he decides to subtract 200cm^3 from each volume. His results can be summarised as:
Σ(x-200) = 17000
Σ(x-200)^2 = 86000000

I have found the coded mean (2325) and the coded standard deviation (2497). The last part is to calculate the value of Σ(x-300). Please could someone tell me how to do it or give me hints on how to do it, thanks.

You've already worked out the sum of (x-200), so what will be the difference between that and the sum you're looking for?

Thanks but im still not sure how to do it. The answers in the back say it is 16200 but i dont know how they got it.