Question

A,B and C working together can plough a field in 4 4/5 days. A and C together it in 8 days. How long would B alone take to plough the field.

Answer 1

let in x days A complete work,in y days B and in z days C complete it so
work done by A in one day =1/x (same for B,C)..(i)
it is given that A,B,C complete a work in 4 4/5= 24/5 days
so in one day the do 5/24 work now from (i)
1/x+1/y+1/z=5/24..(ii)
and
1/x+1/z=1/8...(iii)
subtract (iii) from (i)
1/y = 5/24-1/8=2/24=1/12
y=12 so B alone do in 12 days