Sampling and estimation — practice question

During a statistics lesson, 12 people were told to choose a number, $x$, from 1 to 20 inclusive. From the data, Tom obtained $\sum x = 186$ and a standard deviation for $x$ of $4.5$. Assuming Tom’s calculations are correct, find the values of $\sum (x - 10)$ and $\sum (x - 10)^2$.