A shopkeeper earns a profit of 15% after selling a book at 20% discount on the printed price. The ratio of the cost price and printed price of the book is : 

If $$ {x^4}+{1\over{x^4}}$$ then find $$ {x^3}-{1\over{x^3}}=?$$

A cloth merchant on selling 33 metres of cloth obtains a profit equal to the selling price of 11 metres of cloth , the profit is 

Five years ago the sum of the ages of A and B was 58 years. The difference between B's age 8 years ago and A's age 8 years hence is 16 years. The ratio of the present ages of A and B is:

Reshma covers 45 km at a speed of 15 km/h by bicycle, 80 km at a speed of 40 km/h by car, and another 6 km at a speed of 2 km/h on foot. Find her average speed for the whole journey (correct to 2 decimal places).

A crosses a rectangular field at a speed of 52 m / min along its diagonal in 15 seconds and B crosses the ground at the same time by walking at a speed of 68 m / min along its arms. The area of the field is

16 boys or 12 women can do a piece of work in 28 days. In how many days will the same work be done by 4 boys and 4 women, if they all work together?

The least number which when divided by 4, 6, 8 and 9 leave zero remainders in each case and when divided by 13 leaves a remainder of 7 is: