<PRE><B>Question 542446</B>
&lt;br&gt;&lt;font face=&quot;Tahoma&quot;&gt;This is a fairly standard &quot;rate of work&quot; problem.&lt;br&gt;

The standard way to solve these is using this formula:&lt;br&gt;

{{{1/A+1/B=1/T}}}&lt;br&gt;

where A is the time taken by A, B is the time taken by B, and T is the time taken when they work together.&lt;br&gt;

This can also be extended to more than two different workers, machines, etc.&lt;br&gt;

So in our case, time A is 15, and time B is 12.  Let&#39;s solve:&lt;br&gt;

{{{1/15+1/12=1/T}}}&lt;br&gt;

Find a common denominator of 15 and 12 (it&#39;s 60):&lt;br&gt;

{{{4/60+5/60=1/T}}}&lt;br&gt;

{{{9/60=1/T}}}&lt;br&gt;

{{{9*T=60}}}&lt;br&gt;

{{{T=20/3}}} which is about 6.667 minutes which makes sense!&lt;br&gt;

********************************************************************&lt;br&gt;

More information:&lt;br&gt;

Notice that we didn&#39;t use the fact about the 300 pages?&lt;br&gt;

The important thing is that copier A and B both did the exact same job.&lt;br&gt;

We would have a LITTLE more work to do if the jobs were different.&lt;br&gt;

In that case we would just need to convert one of the jobs so that it was the equivalent of the other one.&lt;br&gt;

For example if it said copier A did 300 pages in 12 minutes, and copier B did 900 pages in 60 minutes,&lt;br&gt;

we would need to convert A to 900 pages, or convert B to 300 pages.&lt;br&gt;

I would convert copier A to 900 pages by multiplying both values by 3.&lt;br&gt;

Hence, copier A could do 900 pages in 36 minutes.&lt;br&gt;

Then we could proceed with the problem once again as we did above.&lt;br&gt;

I hope this helps!</PRE>