At Frank's Fruit Market, 3 bananas cost as much as 2 apples, and 6 apples cost as much as 4 oranges. How many oranges cost as much as 18 bananas?
$\mathrm {(A)} 6\qquad \mathrm {(B)} 8\qquad \mathrm {(C)} 9\qquad \mathrm {(D)} 12\qquad \mathrm {(E)} 18$
$18$ bananas cost the same as $12$ apples, and $12$ apples cost the same as $8$ oranges, so $18$ bananas cost the same as $8 \Rightarrow \mathrm {(B)}$ oranges.