The sum of the ages of the father the and the son is 44 years. After 8 years, the age of the father will be double the age of the son. What is the age of the son ?

At a certain rate of simple interest Rs 2000 amounted to Rs 2400 in four years. If the rate of interest be decreased by 2%, what will be the amount after 4 years ?

In a stream running at 2 kmh'1, a boat goes 60 km upstream and back again to the starting point in 16 hours. What is the speed of the boat in still water ?

Two trains are moving in opposite directions at speeds of 24 kmh"1 and20kmh'. The faster train crosses a man in the slower train in 9 seconds. What is length of the faster train ?