Since, X is thrice as good a workman as Y. ∴ Ratio in their working efficiency =3:1 Then, ratio between the time taken by them to complete the work =1:3 Let X can complete the work in X days and Y in 3x days. According to the question, 3x−x=40⇒2x=40 ⇒x=20 ∴ Working efficiency of both