Question 128914
The first worker in 6 days does 6/18 =1/3 of the work
The second worker in 6 days does 6/24 =1/4 of the work
The third worker in 6 days does 6/30 =1/5 of the work


so altogether can do 1/3+1/4+1/5 of the work
note that  1/3+1/4+1/5 = (20+15+12)/60 = 27/60 = 9/20

R: 9/20 of the work