The value of $\frac{(0.67 \times 0.67 \times 0.67)-(0.33 \times 0.33 \times 0.33)}{(0.67 \times 0.67)+(0.67 \times 0.33)+(0.33 \times 0.33)}$ is:

$\frac{180 \times 15 - 12 \times 20}{140 \times 8 + 2 \times 55} = ?$

Simplify: $2 \div [2 + 2 \div \{2 + 2 \div (2 + 2 \div 3)\}]$

The value of: $\sqrt{\frac{0.324 \times 0.081 \times 4.624}{1.5625 \times 0.0289 \times 72.9 \times 64}}$

Seema bought $20$ pens,$8$ packets of wax colours,$6$ calculators,and $7$ pencil boxes. The price of a pen is $Rs. 7$,a packet of wax colour is $Rs. 22$,a calculator is $Rs. 175$,and a pencil box is $Rs. 14$ more than the combined price of one pen and one packet of wax colours. How much amount did Seema pay to the shopkeeper? (in $Rs.$)

If $x = \frac{4 \sqrt{ab}}{\sqrt{a} + \sqrt{b}}$,then what is the value of $\frac{x + 2 \sqrt{a}}{x - 2 \sqrt{a}} + \frac{x + 2 \sqrt{b}}{x - 2 \sqrt{b}}$ (when $a \neq b$)?