Determine the $L.C.M.$ of $\frac{2}{5}, \frac{3}{10}$ and $\frac{6}{25}$.

The $LCM$ of two numbers is $48$. The numbers are in the ratio $2:3$. Find the sum of the numbers.

The $LCM$ of two prime numbers $x$ and $y$ $(x > y)$ is $161$. Find the value of $(3y - x)$.

The $HCF$ and $LCM$ of two numbers are $21$ and $84$ respectively. If the ratio of the two numbers is $1:4$,then the larger of the two numbers is

If the students of $9^{th}$ class are arranged in rows of $6, 8, 12$ or $16$,no student is left behind. The possible number of students in the class is

The traffic lights at three different road crossings change after every $48\, seconds,$ $72\, seconds$ and $108\, seconds,$ respectively. If they all change simultaneously at $8: 20: 00$ $hours,$ then they will again change simultaneously at