Question: A cat eats nine sausages in 30 minutes. A dog can eat the same number of sausages in 2/3 the amount of time the cat takes. Calculate the average time the two take the eat the sausages.
Find the solution. 
Answer: 
If the cat takes 30 minutes to eat the sausages, the dog takes 2/3*30 = 20 minutes.
The total amount of time the cat and the dog take to eat the sausages is 20+30 = 50 minutes.
The average time in minutes that the two take to eat the sausages is 50/2 = 25 minutes.