⇒ 2(A + B + C) = 47 (Efficiency) ⇒ A + B + C = 23.5 ---- (1) ⇒ B + C = 12 ---- (2) From (1) and (2) ⇒ A = 11.5 ⇒ A alone can do the same work = total work/efficiency of A ⇒ A alone can do the same work = 300/11.5 = 600/23 days ∴ A alone can do the same work in 600/23 days.