AMC12 2007 12B, Problem 4

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?

Solution: $18$ bananas cost the same as $12$ apples, and $12$ apples cost the same as $8$ oranges, so $18$ bananas cost the same as $8 $ oranges. $\fbox{8}$.

Answer: 8