6 men and 8 boys can finish a piece of work in 10 days. While 26 men and 48 boys can finish the work in 2 days. In how many days a group of 15 men and 20 boys do that work?

04

 let M denotes the work done by a man in 1 day and B denotes the work done by a boy in 1 day.

total work = efficiency × number of days

Now, 6 men and 8 boys do the work in 10 days , total work = 10(6M+8B)

Similarly, 26 men and 48 boys do the work in 2 days ,

total work =  2(26M+48B)

we get ,  10(6M+8B) = 2(26M+48B)

 60M + 80B = 52M + 96B

 1M = 2B

Thus, if we say 15 men and 20 boys, we means; = 30B + 20B = 50B.

Now, (6M + 8B) do the work in 10 days.

 (12B + 8B) do the work in 10 days.

 20B do the work in 10 days.

1B do the work in 10×20 = 200 days.

50B will do the work in \(\frac{200}{50}\) = 4 days.