When the mean, median, and mode of the list
10,2,5,2,4,2,xare arranged in increasing order, they form a non-constant arithmetic progression. What is the sum of all possible real values of x?
<spanclass=′latex−bold′>(A)</span>3<spanclass=′latex−bold′>(B)</span>6<spanclass=′latex−bold′>(C)</span>9<spanclass=′latex−bold′>(D)</span>17<spanclass=′latex−bold′>(E)</span>20