Suppose the time taken for the repairman to fix one pair of shoes is x, time taken by the assistant will be 1.5x. The number of shoes repaired by shoe man in an hour will be: 1/x the number of shoes prepared by assistant in 1 hour will be: 1/1.5x the number of shoes repaired by both of them in 1 hour will be: 8/20 hence; 1/1.5x+1/x=8/20 2.5/(1.5x)=2/5 cross-multiplying our equation we get: 2.5*5=1.5x*2 7.5=3x x=7.5/3 x=2.5 hours therefore we conclude that it takes the repairman 2.5 hours to fix one pair of shoes.