Freshers India

A can do a piece of work in 80 days. He works at it for 10 days B alone finishes the remaining work in 42 days. In how much time will A and B working together, finish the work?                        

A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :                        

A man can do a piece of work in 5 days, but with the help pf his son, he can do it in 3 days. In what time can the son do it alone?                        

A is twice as good a workman as B and together they finish a piece in 18 days. In how many days will A alone finish the work?                        

A can lay railway track between two given stations in 16 days and B can do the same job in 12 days. With help of C, they did the job in 4 days only. Then, C alone can do the job in:                        

Sakshi can do a piece of work in 20 days. Tanya is 25% more efficient than Sakshi. The number of days taken by tanya to do the same piece of work is