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

$A$ person was to multiply a fraction by $\frac{6}{7}$. Instead,he divided the fraction by $\frac{6}{7}$ and got an answer which exceeds the correct answer by $\frac{1}{7}$. The correct answer is:

$3 \div \left[ (8 - 5) \div \left\{ (4 - 2) \div \left( 2 + \frac{8}{13} \right) \right\} \right] = ?$

$(7.5 \times 7.5 + 37.5 + 2.5 \times 2.5)$ is equal to

If $a+b+c=1$ and $ab+bc+ca=\frac{1}{3}$,then $a:b:c$ is

$A$ sum of $Rs. 1360$ has been divided among $A, B$ and $C$ such that $A$ gets $\frac{2}{3}$ of what $B$ gets and $B$ gets $\frac{1}{4}$ of what $C$ gets. $B$'s share is (in $Rs.$)