Question

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 5 hours. After Bettina has been working for 1 hour comma Kane is able to join her. How much longer will it take them working together to remove the rest of the​ snow?

Answer 1

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.

Understand?