Following a severe snowstorm, Ken and Bettina Reeves must clear their driveway and sidewalk. Ken can clear the snow by himself in 3 hours, and Bettina can clear the snow by herself in 4 hours. After Bettina has been working for 1 hour, Kane is able to join her. How much longer will it take them working together to remove the rest of the snow?

Determine how much of the job they have finished by calculating:

2/4 + 2/6 = 1/2 + 1/3 = 5/6 of the job has been done.

So, they have 1/6 of the job to go.

Then we write the following fractional equation:

t/4 + t/6 = 1/6

Multiply all by 12 (the LCD) and get

3t + 2t = 2

5t = 2

t = 2/5 hour = 24 minutes.

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