Arun is twice efficient as Bala and together they do the same work in as much time as Chitra and David together. If Chitra and David can complete the work in 20 and 30 days respectively, working alone, then in how many days A can complete the work individually?
Answer with explanationAnswer: Option D
1/x + 1/2x = 1/20 + 1/30
3/2x = 1/12
Number of days taken by Arun = 18 days