One maid can clean the house three times faster than another

One maid can clean the house three times faster than another. Working together they can clean the entire house in 3 hours. How long would it take the faster maid cleaning alone?
I would like you to do this problem step by step and explain because it\'s hard for me to understand.Thanks A lot!

Solution

Faster maid DATA:
time = x hr/job ; rate = 1/x job/jhr
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Slower maid DATA:
time = 3x hr/job ; rate = 1/3x job/hr
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Together DATA:
time = 3 hr/job ; rate = 1/3 job/hr
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Equation:
rate + rate = together rate
1/x + 1/3x = 1/3
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Multiply thru by 3x to get:
3 + 1 = x
x = 4 hrs (time for the faster maid to do the job)