Simplify : $$ {(7) ^{2} ÷(7^{1\over 2})^{4}}$$

If a² + a + 1 = 0 then the value of a⁹ is. 

 If $$ x=\sqrt{(1.96)}-\sqrt{(0.04)}$$ then the value of x is

The product of two whole numbers is 37. The square root of the difference of the numbers is

If $$ {\sqrt{1+{473\over{256}}}=1+{x\over 16}}$$ then what does x equal to ?

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

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?