Vinay and Praveen working together can paint the exterior of a house in 6 days. Vinay by himself can complete the job in 5 days less than Praveen. How long will it take Vinay to complete the job.

Peri needs 4 hours to complete a work. His friend Yuvan needs 6 hours to complete the same work. How long will take to complete if they work together?

Arul, Ravi, and Ram working together can clean a store in 6 hours. Working alone, Ravi takes twice as long to clean the store as Arul does. Ram needs three times as long as Arul does. How long would it take each if they are working alone?