The simplification of $1+\frac{1}{1+\frac{1}{1-\frac{2}{3}}}$ yields the result

Determine the value of $x$. If $x = \frac{(943 + 864)^{2} - (943 - 864)^{2}}{(1886 \times 1728)}$

$\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)\left(1-\frac{1}{5}\right) \ldots \left(1-\frac{1}{25}\right)$ is equal to

The sum of the first $20$ terms of the series $\frac{1}{5 \times 6} + \frac{1}{6 \times 7} + \frac{1}{7 \times 8} + \cdots$ is

$12 \frac{5}{7} + 23 \frac{3}{5} - 14 \frac{1}{3} = 28 \frac{4}{7} - ?$

In an examination,a student scores $4$ marks for every correct answer and loses $1$ mark for every wrong answer. If he attempts in all $60$ questions and secures $130$ marks,the number of questions he attempts correctly is