Question

Le can clean the house in 9 hr, while Tran needs 6 hr. How long will it take them to clean the house if they work together?

Answer 1

@Rishi123 @kropot72 Do you guys know?

Answer 2

In one hour Le working alone can clean 1/9 of the house, and in one hour Tran working alone can clean 1/6 of the house. Therefore working together for one hour, Le and Tran can clean:
(1/9) + (1/6) of the house.
@Abbles Can you follow so far?

Answer 3

@Abbles Are you there?

Answer 4

Yes... so where would I go from there?

Answer 5

(1/9) + (1/6) = x ? Or maybe (1/9) + (1/6) = (1/x) ?

Answer 6

\[\large \frac{1}{9}+\frac{1}{6}=\frac{5}{18}\]
Therefore in one hour, working together, Le and Tran can clean 5/18 of the house. So in 1/5 of an hour they can clean 1/18 of the house, meaning that they must work 18/5 hours together to clean the whole house.

Answer 7

Oh my gosh you are brilliant. Thank you so much! That cleared it up big time.

Answer 8

So together it takes them 3.6 hours. Thank you very much

Answer 9

You're welcome :)