The equation $3x - 2y + 5 = 0$ can be written as:

In a rectangle,the length is $3$ less than twice its width. The perimeter of the rectangle is $100$. Represent this situation as a pair of linear equations in two variables.

The cost of $2\,kg$ of apples and $1\,kg$ of grapes on a day was found to be Rs. $160$. After a month,the cost of $4\,kg$ of apples and $2\,kg$ of grapes is Rs. $300$. Represent this situation as a pair of linear equations in two variables.

Solve the following pair of linear equations by the method of elimination: $0.3 x + 0.4 y = 1$ and $6 x + 8 y = 20$.

If the following pair of equations has infinite solutions,then find the value of $k$:
$5x + 2y = k$
$10x + 4y = 3$

For eliminating $y$ from the equations $3x - 2y = 1$ and $5x + y = 6$,the second equation should be multiplied by