The traffic lights at three different road crossings change after every $72$ $\mathrm{seconds}$, $108$ $\mathrm{seconds}$, and $132$ $\mathrm{seconds}$, respectively. If they change simultaneously at $7$ $\mathrm{a}.\mathrm{m}.$, at what time will they change again simultaneously?

Evaluate: $a+b-c,$ if $a=5, b=4$ and $c=-5$

There are $36$ rows in a cinema hall. Find the minimum number of chairs in each row if the capacity of the cinema hall is $600$ people at a time.

A place is $40 \mathrm{m}$ above the sea level and another is $31 \mathrm{m}$ below the sea level. What is the distance between the two places?

The number of students in each section of a school is $35$. The fee paid by each student is $₹ 950$ per month. If there are $40$ sections in the school, what is the total collection of fees in a month?

Reecha mixes $\frac{1}{4}$ $\mathrm{litre}$ of water with $\frac{3}{8}$ $\mathrm{litre}$ of lemon squash. How much mixture does she get?

A brick weighs $2\frac{1}{4} \mathrm{kg}$. A stone is $1\frac{1}{5} \mathrm{kg}$ lighter than the brick. Find the weight of the stone.