Question

a and b together can do a piece of work in 12 days. b and c together can do it in 15 days. if a is twice as good as c, in how many days a alone will do the same work?

Answer 1

it should be 30 days

Answer 2

how do you solve this can you explain...

Answer 3

let the work done by a,b and c in one day be;
A,B and C , respectively

1st case: a & b
work done = 12A+12B
2nd case: b & c
work done= 15B+15C

now work done in both case is same
so, 12A+12B=15B+15C
=> 12A=3B+15C
=> 4A= B+5C......(i)

also it is given that a is twice as good as c
so A=2C
put this in eq(i)
=> 8C= B+5C
=> B=3C
now again writing the work done

15B+15C= 15x3C + 15C= 60 C= 30A

that means A alone can do the work in 30 days

i hope the explanation is clearly understood