<PRE><B>Question 381940</B>
 it takes rob 4 hours to paint a room. it takes darrin 3 hours to paint a room the same size. how long it take them to paint a similar sized room together 
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Rob rate = 1/4 job/hr
Darrin rate = 1/3 job/hr
Together rate = 1/x job/hr
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Equation:
rate + rate = together rate
1/4 + 1/3 = 1/x
Multiply thru by 12x to get:
3x + 4x = 12
7x = 12
x = 12/7
x = 1hr and (5/12)60 min
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x = 1 hr and 25 min
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Cheers,
Stan H.</PRE>