4 men or 6 women or 10 children can paint a house in 5 days. The painting is given to a couple and their 5 sons. They finish the job in?

4 men = 6 women = 10 children
⇒ 1 man = 5/2 children
1 women = 5/3 children
Now, 1 couple + 5 children = 1 man + 1 women + 5 children
= (5/2) + (5/3) + 5 = 55/6 children
According to the formula
M₁D₁ = M₂D₂
⇒ 10 x 5 = (55/6) x D₂
∴ D₂ = 60/11 days
= 5⁵/₁₁ days