First write out the prime factorizations of the denominators:
before, we've got exactly one repeat 3, so we can throw one of them
out. Therefore, rather than taking 2 x 2 x 3 x 3 x 3 x 5, we just have
to take 2 x 2 x 3 x 3 x 5. Only slightly less work, but we'll take it.
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