Word problem

one peice of work in four days plus one peice of work in six days equals one peice of work in x days

 

Question: Suppose A and B are eating potato chips from the same bag. It would take A 4 minutes to eat all the chips if B wasn't there. It would take B 6 minutes to eat all the chips if A wasn't there. How long will it take the two of them to finish that bag of chips?

Hint: In one minute, A eats 1/4 of the chips and B 1/6 of the chips, so 1/4+1/6 of the bag will be eaten each minute. If they keep eating for x minutes, they will have eaten (1/4+1/6)x of the bag. The bag will be empty when this equals 1, so all you have to do is to solve the equation (1/4+1/6)x=1.

 

Fredrik posted a very pedagogical hint :
Suppose A and B are eating potato chips from the same bag. :rofl: :rofl:
Doubtlessly students must pay more attention to potato chips than to abstract pieces of work.