Speed of a boat in still water is 6 km/hr and speed of the current is 2 km/hr. If boat takes four hours more in upstream than in the downstream to cover ‘D’ km, then find time take by boat to cover ‘D’ km in still water?

If the speed of the boat in still water is 20 km / h and the speed of the stream is 5 km / h, then how long will it take for the ferry to travel 100 km with the speed of the stream?

If the difference of interest of two banks of Rs 500 is Rs 2.50, find the difference between their rates.

On selling an article for Rs.240, a trader loss of 10%.In order to gain 10%, he must sell that article for -

Two circles having radii 5 units intersect each other in such a way that each of them passes through the centre of the other. Then the length of their common chord is

The top of two poles of height 24 m and 42 m are connected by a wire. If the wire makes an angle of 60° with the horizontal, then the length of the wire is

The price of jewelry , passing through three hands. rises on the whole by 65 %. If the first and the second sellers earned 20 % and 25 % profit respectively, the profit earned by the third seller is 

Find the area of a quadrilateral whose diagonal is 10 cm. And the length of the length put on it is 6 cm and 5 cm respectively.