arithmetic - a wall construction can be done by 6 men and 5 women in 6 days or 3 men and 4 women in 10 days it can be done by 9 men and 15 women in - skillgun

Let 1 mans 1 days work =x and 1 woman 1 days work = y.
Then, 6x+5y = 1/6 ,
3x+4y = 1/10
On solving, we get x = 1/54 and y = 1/90
(9 men + 15 women)s 1 days work = (9/54) + (15/90) = 1/3
They will finish the work in 3 days.