Question 1076672
m paints a house in half an hour. Jane paints a house in 1/5 of an hour. If Jim works for 10 minutes and then Jane joins him, how long will it take them to complete 1 whole house together? 
I'm not sure if I'm doing this correctly, please help! 
I set up the problem to first figure out how much work Jim has done prior to Jill joining. 
Jim paints a house in a half hour :: rate = 1/30 job/min
He works for 10 minutes 
Jim 1/30 *10 =  1/3 job
Now work total is 1, thus we take 1-.3 = 2/3 job left 
Jane now joins who paints at rate of 1/5 job/hr (1/5 an hour being 12 minutes) 
t(1/30 + 1/12) = 2/3 job
t((12+30)/(12*30)) = 2/3
t(42/360) = 2/3
t = (360/42)(2/3) = 120/21 = 5.71 min =  5 min 42 sec
t is time to finish the job together.
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Cheers,
Stan H.
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