Question 1144569
>>Trent can deliver his newspapers in 20 minutes.<< 
<pre>
So Trent's delivery rate is 1 route per 20 minutes:

{{{matrix(1,5,
(matrix(2,1,"Trent's",rate)),
""="",
matrix(1,2,1,route)/matrix(1,2,20,minutes),
""="",
matrix(1,2,1/20,route/minute))}}}
</pre>
>>It takes Lois 30 minutes to do the same route.<< 
<pre>
So Lois's delivery rate is 1 route per 30 minutes:

{{{matrix(1,5,
(matrix(2,1,"Lois's",rate)),
""="",
matrix(1,2,1,route)/matrix(1,2,30,minutes),
""="",
matrix(1,2,1/30,route/minute))}}}

When they work together, their combined rate is the sum of their rates:

{{{matrix(1,15,
(matrix(3,1,Their,combined,rate)),
""="",
matrix(1,2,1/20,route/minute),
""+"",
matrix(1,2,1/30,route/minute),
""="",
matrix(1,2,1/20+1/30,route/minute),
""="",
matrix(1,2,3/60+2/60,route/minute),
""="",
matrix(1,2,5/60,route/minute),
""="",
matrix(1,2,1/12,route/minute),
""="",
matrix(1,2,1,route)/matrix(1,2,12,minutes)

)}}}
</pre>
>>How long would it take them to deliver the newspapers if they work together?<< 
<pre>
Answer: 1 route in 12 minutes.

Edwin</pre>