SOLUTION: if 2 people work at washing 5 cars and one can do all 5 on their own in 36 minutes and the other can do all 5 on their own in 42 minutes, how long does it take to wash all 5 workin

Question 885105: if 2 people work at washing 5 cars and one can do all 5 on their own in 36 minutes and the other can do all 5 on their own in 42 minutes, how long does it take to wash all 5 working together?
Found 2 solutions by ankor@dixie-net.com, josmiceli:
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
if 2 people work at washing 5 cars and one can do all 5 on their own in 36 minutes and the other can do all 5 on their own in 42 minutes, how long does it take to wash all 5 working together?
:
Let t = time required when both together
Let the completed job = 1 (the washing of 5 cars)
:
Each will to a fraction of the job, the two fractions add up to 1
+ = 1
multiply by the least common multiple of 36 & 42: 252
252* + 252* = 252
Cancel the denominators and you have:
7t + 6t = 252
13t = 252
t = 252/13
t = 19.4 minutes working together
:

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Since it's only about washing 5 cars, call that 1 job
1st person's rate of washing:
( i job ) / ( 36 min )
2nd person's rate of washing:
( 1 job ) / ( 42 min )
--------------------------
Let = the time to finish job
working together
Add their rates of working to get
their rate working together
--------------------------

Multiply both sides by

It will take them 19 and 5/13 min woking together
check:

OK

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