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Sally can paint a room in 7 hours while it takes Steven 3 hours to paint the same room. How long would it take them to paint the room if the room if they worked together?

 

It would take __ hours

yojaymarojas  May 14, 2017
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These  are easy  to solve when we know the rates

 

Sally can paint 1/7  of a room in 1 hour

Steven can paint 1/3 of a room in 1 hour

 

So.......

 

(1/7)  + (1/3)  =  [ 7 + 3 ] / 21  =   10/21

 

Invert this fraction    =  21 /10   =   2.1  hrs.  working together

 

 

 

cool cool cool

CPhill  May 14, 2017

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