If $$ {2^{2n-1}}={1\over8^{n-3}}$$,then the value of n is:

A circle and a rectangle have the same perimeter. The sides of the rectangle are 18 cm and 26 cm. The area of the circle is:

A book seller sells a book at a profit of 10 %. If he had bought it at 4 % less and sold it for Rs. 6 more. he would have gained $$18{3\over4}\%$$. The cost price of the book is 

If a=2b/3, b=2c/3, and c=2d/3, then find the ratio of b and d:

If $$ {tan3A=cot{(2A+40)}}$$ then find the value of $$ {tan^2{3A}}+{cot^{4}3A}$$.

A seller gives 15% discount on an item, if he marked up the price of item 40% above C.P and while selling he cheats the buyer by giving 10% less in weight. Find this overall profit percent (approximately).

The ratio of speeds of A is to B is 2:3 and therefore A takes 20 minutes less time than B takes. What is the ratio of time taken by A and B?

The two trains cross each other in 12 seconds, moving in the opposite direction, and they take 60 seconds to travel in the same direction. both trains can have speed in (m/sec).