What will come in the place of the question mark $(?)$ in the following expression?
$59.88 \div 12.21 \times 6.35 = ?$

If $1^{3}+2^{3}+\cdots+9^{3}=2025,$ then the value of $(0.11)^{3}+(0.22)^{3}+\cdots+(0.99)^{3}$ is close to

$(2 + \frac{3}{x}) \times (y + \frac{1}{2}) = \frac{31}{4}$,find the values of $x$ and $y$ if $x$ and $y$ are positive integers.

What will come in the place of the question mark $(?)$ in the following expression?
$\frac{343 \times 49}{216 \times 16 \times 81} = ?$

The value of $\frac{2^{1 / 2} \cdot 3^{1 / 3} \cdot 4^{1 / 4}}{10^{-1 / 5} \cdot 5^{3 / 5}} \div \frac{3^{4 / 3} \cdot 5^{-7 / 5}}{4^{-3 / 5} \cdot 6}$ is

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