Jagdish can Build a Wall in 10 days. Narender can Build the Same Wall in 12 days while Submitting 15 Days to do the same job. Which two Should be employed to finish the job in 6 days

Answer: Work that Jagdish does in 1 day = 1/10

Work that Narender does in one day = 1/12

One day work done by Sumit = 1/15

However, work that is done by Sumit and Jagdish in 1 day is = 

1/10 + 1/15

= (3 + 2)/30

= 5/30 = 1/6

The total number of days required by Sumit and Jagdish to complete work = 6 days.