If  $${3-5x\over 2x}+{3-5y\over 2y}+{3-5z\over 2z}=0$$ then the value of  $${2\over x}+{2\over y}+{2\over z}$$ is:

A shopkeeper increases the price of an object by 40 % and then sells it at 25 % discount on the marked price. If the selling price of such an object be ₹ 2100, its cost price for the shopkeeper was? 

A article is marked at Rs. 65 and a customer buys it for Rs. 56.16 and got two successive discount of 4% and k%. Find the value of   k?

The value of $$ {3sin30°-4sin^{3}30°}$$

If a machine consumes k/5 kilowatts of power every t hours, how much power in kilowatts, will three such machines consume in 10 hours? 

If 0.5x + 0.7y=0.5 and 0.7x + 0.5y=0.7,then the value of x+y is

Greatest among the numbers
$$^{3}\sqrt{9},\sqrt{3},\ ^{4}\sqrt{16},\ ^{6}\sqrt{180}$$ is