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?

The area of two equilateral triangles are in the ratio 25 : 36 . Their altitudes will be in the ratio: 

A loss of 19% gets converted into a profit of 17% when the selling price is increased by Rs. 162. The cost price of the article is 

Find the inradius of a triangle having sides 13, 14 and 15 units.

In the given filed the area under triangular shape is

The distance between two cities A and B is 330 km. A train starts from A at 8 a.m. and travels towards Bat 60 km / hr. Another train starts from Bat 9 a.m. and travels towards A at 75 km/hr. At what time do they meet?

If A and B are the HCF and LCM respectively of two algebraic expressions x and y, and A + B = x + y, then the value of A³ + B³ is 

Select the number that will come in place of the question mark (?) in the following mathematical statement.

$${5\over 9} \ of \ {11\over 14}\ 42\% \ of \ 540=?^2 -45 $$