............ is not a linear equation in two variables.

Jamila sold a table and a chair for $Rs.\, 1050,$ thereby making a profit of $10\%$ on the table and $25\%$ on the chair. If she had taken a profit of $25\%$ on the table and $10\%$ on the chair,she would have got $Rs.\, 1065.$ Find the cost price of each (in $Rs.$).

The ages of two girls are in the ratio $5:7$. Eight years ago,their ages were in the ratio $7:13$. Represent this situation as a pair of linear equations in two variables.

In a two-digit number,the digit at the ten's place is double the digit at the unit's place. If the digits of the number are interchanged,the new number so formed is $27$ less than the original number. Find the original number.

Solve the following pair of linear equations:
$x + y = 3.3$
$\frac{0.6}{3x - 2y} = -1$,where $3x - 2y \neq 0$

The length of a rectangle is five less than thrice its breadth. The perimeter of a rectangle is $110$. If we take $l$ as length and $b$ as breadth,then which of the following equations represents the relationship between length and breadth?