Bunuel wrote:

A machine puts c caps on bottles in m minutes. How many hours will it take to put caps on b bottles?

A. 60bm/c

B. bm/60c

C. bc/60m

D. 60b/cm

E. b/60cm

A machine puts c caps on bottles in M minutes. A bottle can only have 1 cap, so this means that in M minutes, the machine will cap C bottles

\(\frac{M minutes}{C bottles}\)

How many hours will it take to put caps on B bottles? This is a comparison ratio:

\(\frac{M minute}{C bottles}\) * \(\frac{1 hour}{60 minutes}\) = \(\frac{X hours}{B bottles}\)

This becomes:

\(\frac{(M minute)(B bottles)(1 hour)}{(C bottles)(60 minutes)}\) = \(x hours\)

Simplify to:

\(\frac{mb}{60c}\) = \(x hours\)

This question's only difficulty is seeing that they want you to do a comparison between c bottles and b bottles. They intentionally made the letters confusing for those that could only see b should stand for bottles.