For any two real numbers a and b.

a-b2+b-a2 is

In figure, DE || BC. If DE = 3 cm, BC = 6 cm and area of ΔADE = 15 sq cm, then the area of ΔABC is

The maximum number of common tangents that can be drawn to two disjoint circles is

If m+n=1, then the value of m3+n3+3mnis equal to

If a+1a=1,then the value of a2-a+1a2+a+1 is a≠0

It takes eight hours for a 600 km journey, if 120 km is done by train and the rest by car. It takes 20 minutes more, if 200 km is done by train and the rest by car. The ratio of the speed of the train to that of the car is:

5% more is gained by selling a watch for Rs. 350 than by selling it for Rs. 340. The cost price of the watch is

The number of pupils of a class is 55. The ratio of the number of male pupils to the number of female pupils is 5: 6. The number of female pupils is

A shop keeper earns a profit of 12% on selling a book at 10% discount on the printed price. The ratio of cost price to the printed price of the book is