As per question, ratio of efficiency of P and Q i.e. 3 : 1 So, total efficiency of (P + Q) = 4 Then, ratio of time taken by P and Q is 1 : 3 Let time taken by P is X days So time taken by Q is 3X days Time taken by P = time taken by Q – 60 days X = 3X – 60 2X = 60 X = 30 days Eff.P+Q×TP+Q = Eff.P×TP 4XTP+Q = 3 × 30 TP+Q = 90 days TP+Q = (90/4) days TP+Q = 22(1/2) days