One hundred students at Century High School participated in the AHSME last year, and their mean score was 100. The number of non-seniors taking the AHSME was 50% more than the number of seniors, and the mean score of the seniors was 50% higher than that of the non-seniors. What was the mean score of the seniors?<spanclass=′latex−bold′>(A)</span>100<spanclass=′latex−bold′>(B)</span>112.5<spanclass=′latex−bold′>(C)</span>120<spanclass=′latex−bold′>(D)</span>125<spanclass=′latex−bold′>(E)</span>150