A large rectangle is partitioned into four rectangles by two segments parallel to its sides. The areas of three of the resulting rectangles are shown. What is the area of the fourth rectangle?
[asy]
draw((0,0)--(10,0)--(10,7)--(0,7)--cycle);
draw((0,5)--(10,5));
draw((3,0)--(3,7));
label("6", (1.5,6));
label("?", (1.5,2.5));
label("14", (6.5,6));
label("35", (6.5,2.5));
[/asy]<spanclass=′latex−bold′>(A)</span>10<spanclass=′latex−bold′>(B)</span>15<spanclass=′latex−bold′>(C)</span>20<spanclass=′latex−bold′>(D)</span>21<spanclass=′latex−bold′>(E)</span>25