The eighth grade class at Lincoln Middle School has 93 students. Each student takes a math class or a foreign language class or both. There are 70 eighth graders taking a math class, and there are 54 eighth graders taking a foreign language class. How many eighth graders take only a math class and not a foreign language class?
<spanclass=′latex−bold′>(A)</span>16<spanclass=′latex−bold′>(B)</span>23<spanclass=′latex−bold′>(C)</span>31<spanclass=′latex−bold′>(D)</span>39<spanclass=′latex−bold′>(E)</span>70