The best approach to these problems is to get the 1 hr work done by each participant.

To explain:

If ‘A’ can complete a task in 3 hours and ‘B’ can complete the same task in 6 hours, how long will it take if both of them work together to complete the task?

In 3 hrs, A can do = 1 Task (read as complete Task)

In 1 hr, A can do

=\frac{1}{3} Task

Similarly

In 6 hrs, B can do = 1 Task

In 1 hr, B can do

=\frac{1}{6} Task

Therefore the task done by both A and B in 1 hr

=\frac{1}{3} + \frac{1}{6} = \frac{1}{2} Task

Now

\frac{1}{2} Task is done by both A & B in = 1 hr

1 Task (read as complete Task) is done by both A & B in

= 1 / \frac{1}{2} hrs = 2 hrs

Reason for this detail approach is that with this understanding you can solve questions involving more than 2 people and also with complex combinations....

Hope this helps!

Cheers!

JT

_________________

Cheers!

JT...........

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