Blake and Jenny each took four 100 point tests. Blake averaged 78 on the four tests. Jenny scored 10 points higher than Blake on the first test, 10 points lower on the second test, and 20 points higher on both the third and fourth test.
What is the difference between Blake's average on the four tests and Jenny's average on the four tests?<spanclass=′latex−bold′>(A)</span>10<spanclass=′latex−bold′>(B)</span>15<spanclass=′latex−bold′>(C)</span>20<spanclass=′latex−bold′>(D)</span>25<spanclass=′latex−bold′>(E)</span>40