trent can deliver his newspapers in 30 minutes. it takes lois 20 minutes to do the same route. how long would it take them to deliver the newspapers if they work together?
i understand how to do this problem in hours but not minutes...

Question

trent can deliver his newspapers in 30 minutes. it takes lois 20 minutes to do the same route. how  long would it take them to deliver the newspapers if they work together?
i understand how to do this problem in hours but not minutes...

anonymous · Answer

15 minutes.

anonymous · Answer

the book has 12 minutes as the answer....

saifoo.khan · Answer

$$\frac{1}{30} + \frac{1}{20} = \frac1x$$Solve for x to get the time taken if they both do it.

anonymous · Answer

perfect. thank you, i was putting 30 over 60 to try and get the minutes to hours...

anonymous · Answer

Saifoo.khan is correct.  It's basically a rate problem.  Trent can deliver at a rate of 1 package/30 minutes, and Lois at the rate of 1 package/20 minutes.  You add the rates to get the combined rate.  Then take the reciprocal of the resulting rate to get the time required to deliver the package of newspapers.  That leads to the formula that Saifoo.khan stated, and when you solve for x you get 12 minutes.

anonymous · Answer

thank you