Solve the following pairs of equations by the method of elimination:
$x + 3y - 6 = 0$
$2x - y = 5$

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

Solve the following pairs of equations by the method of elimination:
$\frac{x}{2} + \frac{3y}{5} + 1 = 0$
$\frac{x}{2} + \frac{y}{3} - \frac{1}{3} = 0$

Form the pair of linear equations in the following problems,and find their solutions (if they exist) by the elimination method.
The sum of the digits of a two-digit number is $9$. Also,nine times this number is twice the number obtained by reversing the order of the digits. Find the number.

Solve the following pair of linear equations: $\frac{8}{a} - \frac{9}{b} = 1$ and $\frac{10}{a} + \frac{6}{b} = 7$.

Aruna has only $Rs. 1$ and $Rs. 2$ coins with her. If the total number of coins that she has is $50$ and the amount of money with her is $Rs. 75$,then the number of $Rs. 1$ and $Rs. 2$ coins are,respectively