$\frac{5}{8}$ of $4011.33 + \frac{7}{10}$ of $3411.22 = ?$

What is the value of $\frac{5.6 \times 0.36 + 0.42 \times 3.2}{0.8 \times 2.1} ?$

Simplify:
$\frac{3}{10} \div \frac{3}{7} \text{ of } \left(2 \frac{3}{10} + 2 \frac{3}{5}\right) + \frac{1}{5} \div 1 \frac{2}{5} - \frac{2}{7}$

If $x>1$ and $x^{2}+\frac{1}{x^{2}}=83,$ then $x^{3}-\frac{1}{x^{3}}$ is

If $5 \sqrt{5} \times 5^{3} \div 5^{-\frac{3}{2}} = 5^{a+2},$ then the value of $a$ is

The value of $0.008 \times 0.01 \times 0.0072 \div (0.12 \times 0.0004)$ is