Prashant purchases $2$ mobiles and $3$ memory cards for Rs. $6500$. The cost of one mobile and one memory card is Rs. $2950$. Represent this as a pair of linear equations in two variables.

Which of the following is a linear equation in two variables?

The pair of equations $2x + y - 4 = 0$ and $x + 2y - 5 = 0$ has........

In a two-digit number,the digit at unit's place is $x$ and the digit at ten's place is $y$. The number obtained by interchanging the digits is ...........

There are some students in the two examination halls $A$ and $B$. To make the number of students equal in each hall,$10$ students are sent from $A$ to $B$. But if $20$ students are sent from $B$ to $A$,the number of students in $A$ becomes double the number of students in $B$. Find the number of students in the two halls.

The total cost of three tables and two chairs is ₹ $3400$. The cost of two tables and three chairs is ₹ $3100$. Then the total cost of a chair and a table is ₹ ...............