A is thrice as good a workman as B and so takes 40 days less than B for doing a job. The time in which they can do the job together is-

Question: A is thrice as good a workman as B and so takes 40 days less than B for doing a job. The time in which they can do the job together is- Solution:Let, A alone takes x days and B alone takes 3x days to complete the work.According to the question, 3x - x = 40⇒ 2x = 40⇒ x = 20So, A takes 20 days and B takes ( 3 × 20) = 60 days Now, ( A+B )'s 1 days work = (1/20) + (1/60) = 4/60= 1/15 ∴ A & B together can do the work in 15 days.