M and N started a business. M invested ₹50,000 more than N for 3 months, while N invested for 7 months. M's share is ₹328 more than that of N, out of a total profit of ₹4,920. Find the capital contributed by M.

Three partners invested in a business in the ratio 8:5:4. They invested their capital for 3 months, 10 months, and 9 months respectively. What was the ratio of their profits?

A started a business with an investment of ₹21,000 and after a few months, B joined him with an investment of ₹15,000. At the end of the year, the total profit was divided between them in the ratio 12 : 5. After how many months did B join the business?