Question

a worker can do a job in 5 hrs and his student can do the same job in 8 hrs. What part of the job is left if they start the job and work together for 2 hrs. What part of the work is left to finish?(picture if you do not understand)

Answer 1

7/20

Explanation:

Let's do this.

The worker can work 1/5 job in an hour and the student can do 1/8 job in an hour. 1/5 + 1/8 = 13/40. The worker and the student together can do 13/40 job in an hour. If we multiply 13/40 by 2, we get 13/20 and that is 2 hours.

So 20/20 - 13/20 = 7/20.

They have 7/20 of the job left to finish.