A alone can do a piece of work in 10 days. A and B together can do the same piece of work in $$\frac{20}{3}$$ days. A, B and C together can do the same piece of work in $$\frac{40}{7}$$ days. In how many days can B and C together do the same piece of work?

A alone can do a piece of work in 10 days.

Work done by A alone in one day = $$\frac{1}{10}$$

A, B and C together can do the same piece of work in $$\frac{40}{7}$$ days.

Work done by A, B and C together in one day = $$\frac{7}{40}$$

B and C together can do the same piece of work in one day = $$\frac{7}{40} - \frac{1}{10}$$

= $$\frac{7}{40} - \frac{4}{40}$$

= $$\frac{3}{40}$$

Number of days taken by B and C together to do the same piece of work = $$\frac{40}{3}$$ days