A bag has Rs.420 in the denomination of Rs.1, Rs. 2 and Rs. 5 coins. The number Rs.1, Rs.2 and Rs.5 coins are in the ratio of 8: 1:5. How many coins of Rs.5 are in the bag?

If the sum and difference of two number are 20 and 8 respectively, then the difference of their squares is: 

In a garden of 42 trees, 3/7 of them are Neem trees and the rest are Mango trees. Find the number of Mango trees.

If 1.5 a=0.04 b then $$ {b-a\over b+a}$$.

If $$ {1\over3} ({12x\over5}-{1\over2})+{6\over5}={7\over6}$$ then what is the value of x?

Find the value of   $$ {(0.75)^3\over1-.75}+[0.75+(0.75)^2+1]$$

What mathematical operation should come at the place of ‘?’ in the equation:
2 ? 6 – 12 ÷ 4 +2 =11.

Assume that
$$\sqrt{3} = 3.605 \ (approximately)  $$
$$\sqrt{130} = 11.40 \ (approximately)  $$
Find the value of
$$\sqrt{1.3} + \sqrt{1300}+\sqrt{0.013}  $$