Ram and Sourav have started working on a project together. Ram can alone complete the work in 15 days while Sourav can complete the work alone in 20 days. After 4 days of work, Sourav took a break of 3 days while Ram continued to work. In how many days, will the project be completed?

Ram's rate = 1/15 work per day. Sourav's rate = 1/20 work per day. Combined rate = 1/15 + 1/20 = 4/60 + 3/60 = 7/60 work per day. Work done in first 4 days together = 4 × (7/60) = 28/60 = 7/15. Remaining work = 1 - 7/15 = 8/15. For next 3 days, only Ram works: work done = 3 × (1/15) = 3/15 = 1/5. Total work done after 7 days = 7/15 + 1/5 = 7/15 + 3/15 = 10/15 = 2/3. Remaining work = 1 - 2/3 = 1/3. Both work together at 7/60 per day. Time needed = (1/3) / (7/60) = 60/21 = 20/7 ≈ 2.86 days. Total time = 4 + 3 + 2.86 = 9.86 days ≈ 9.8 days.