A, B and C together can finish a piece of work in 20 days. A alone can finish the work in 40 days. What part of the work B and C together can finish in a day ?

1/40

A + B + C = 20 days,

A = 40 days,

⇒ Therefore, B+C = 1,

⇒ So, part of the work B and C together can finish in a day = \(\frac{efficiency}{total work}\) = \(\frac{1}{40}\) units.