If books bought at prices from ₹150 to ₹ 300 are sold at prices ranging from ₹ 250 to  ₹350, what is the greatest possible profit that might be made in selling 15 books ?

Two train 120 meters and 160 meters in length are running towards each other on parallel lines at the speed of 70 kmph and 42 kmph respectively. How long will it take to cross each other after they meet?

7 years ago, the ages of A and B were in the ratio of 4: 5 and after 7 years they would be in the ratio of 5: 6. The present age of B is-

$$ {I.2x^{2}-{9x}+10=0}$$
$$ {II.2y^{2}-13y+20=0}$$

Three solid metallic sphere whose radii are 3cm, x cm and 18cm respectively, are melted and recast into a single solid sphere of diameter 38cm. Then find the total surface area of the sphere with radius x cm?

The ratio between the number of sides of two regular polygons is 1 : 2 and the ratio between there interior angles is 2 : 3. The number of sides of these polygons is respectively 

A sum of money lent at simple interest amounts to ₹ 880 in 2 years and to ₹ 920 in 3 years. The sum of money (in rupees) is

A person deposited ₹15,600 in a fixed deposit at 10% per annum simple interest. After every second year he adds his interest earned to the principal. The interest at the end of 4 years is: