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

If x:y=3:2 then the ratio $$ {2\ x^{2}+3\ y^{2}}:{3\ x^{2}}-{2\ {y^{2}}}$$ is equal to

A train travelling at 36 km/h crosses a pole in 25 seconds. How much time (in seconds) will it take to cross a bridge 350 m long?

If A’s income is 40 % less than that of B, how much percent B's income is more than that of A? 

When a mobile is sold at 6 percent profit, it gets Rs. 870 more than it is sold at 6 percent loss. So what is the purchase price of mobile?

If is a positive acute angle and 5 cosθ + 12 sinθ = 13, then find the value of cosθ?

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 : 

The table given below shows the cost price and selling price of four articles.

What is the average value of loss of all articles?