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Ernie can paint a house in just 2 hours. Izzy can paint a house in 5 hours (because she takes breaks to read and sip lemonade  ). Working together, how long will it take them to paint 2 houses?

 Feb 22, 2021
 #1
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Ernie pains 1/2 a house per hour

 

Lizzie pains 1/5 of a house in an hour

 

Together they paint  1/5  +  1/2   =  7/10 of a house in an hour

 

So that is 10/7   hours per house

 

\(\frac{10hours}{7houses}*2 houses= \frac{20}{7}hours\)

 

 

So that is   

2 hours  51minutes and 26 seconds  to the nearest second.

 Feb 22, 2021

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