A man can row 10km/h in still water. If the river is running at 3 km/h, it takes 6 hours more to go upstream than downstream for the same distance. How far is the place in km ?

Two trains of length 100m and 120 m respectively with different speeds pass a pole in 5 sec and 10 sec respectively. In what time will they cross each other when they are moving in the same direction ?

The simple interest on a certain sum of money for 2 years at 8% per annum is Rs 2200. What will be the compound interest at the same rate and for the same time ?

A man 'A' can do a work in 30 days. With the help of another man" B' he can do the same work in 17 days. If they get Rs 2100 for that work, what is the share o f ' B ' ?

The sum of the ages o f ' A ' and ' B ' is 80 years. After 20 years the age of 'A' is twice that of ' B ' . What is the present age o f ' B ' in years ?