Barney Schwinn notices that the odometer on his bicycle reads 1441, a palindrome, because it reads the same forward and backward. After riding 4 more hours that day and 6 the next, he notices that the odometer shows another palindrome, 1661. What was his average speed in miles per hour?<spanclass=′latex−bold′>(A)</span>15<spanclass=′latex−bold′>(B)</span>16<spanclass=′latex−bold′>(C)</span>18<spanclass=′latex−bold′>(D)</span>20<spanclass=′latex−bold′>(E)</span>22