On what sum does the difference between the compound interest and the simple interest for 3 years at 10 % is Rs 31?

If $${4x^2={15^2-9^2}}$$ then the value of x is

A group consists of 25 men and 20 women. The average weight of men is 48 kg and that of women is 30 kg. The average weight of the group is

If 4x+5y=83 and $$ \ {3x\over2y}={21\over22}$$then what is the value of y-x ?

The area of a circle, is 3850 sq.m. What will be its circumference?

In an alloy, the ratio of copper and zinc is 5 : 2. If 1.250 kg of zinc is mixed in 17 kg 500 g of alloy, then the ratio of copper and zinc will be