A can do 7/8 of work in 28 days, B can do 5/6 of the same work in 20 days. The number of days they will take to complete if they do it together is?Options15 7/3 days14 5/7 days13 5/7 days17 3/5 days

To solve this problem, we first need to find out how many days A and B would take to complete the work individually.

1. For A, if 7/8 of the work takes 28 days, then the whole work would take 28/(7/8) = 32 days.

2. For B, if 5/6 of the work takes 20 days, then the whole work would take 20/(5/6) = 24 days.

Now, we know that A can complete the work in 32 days and B can complete the work in 24 days.

The amount of work A can do in one day is 1/32 and the amount of work B can do in one day is 1/24.

So, if they work together, in one day they can do 1/32 + 1/24 of the work.

To find this, we need to find a common denominator for 32 and 24, which is 96.

So, 1/32 becomes 3/96 and 1/24 becomes 4/96.

Adding these together, we get that they can do 7/96 of the work in one day.

Therefore, to find out how many days they would take to complete the work together, we divide the whole work (1) by the amount they can do in one day (7/96), which gives us 96/7 = 13 5/7 days.

So, the answer is 13 5/7 days.