Question

Mr. Fat needs 20 minutes to eat a pound of cereal, while Mr. Thin needs 30 minutes. If they eat together, how long does it take for them to finish off three pounds of cereal? Express your answer in minutes.

Answer 1

36 minutes.

(1/20)x+(1/30)x=1solve for x (x=0.8333333333......)
Considering they take the same times for all 3 pounds,
That would mean that since 1 pound takes 12 minutes, then 3 pounds take 36 minutes