If the pair of equations $\frac{5}{x} - \frac{3}{y} = 9$ and $\frac{3}{x} - \frac{5}{y} = 7$,then $\frac{1}{x} - \frac{1}{y} = \ldots$

If $4x - 12y = 20$,then $5x - 15y = \ldots$

Solve the following pairs of equations:
$\frac{2xy}{x+y} = \frac{3}{2}$
$\frac{xy}{2x-y} = \frac{-3}{10}, \quad x+y \neq 0, 2x-y \neq 0$

Form the pair of linear equations in the following problems and find their solutions (if they exist) by any algebraic method.
The area of a rectangle gets reduced by $9$ square units,if its length is reduced by $5$ units and breadth is increased by $3$ units. If we increase the length by $3$ units and the breadth by $2$ units,the area increases by $67$ square units. Find the dimensions of the rectangle.

For which value$(s)$ of $\lambda$,do the pair of linear equations $\lambda x + y = \lambda^2$ and $x + \lambda y = 1$ have:
$(i)$ no solution?
$(ii)$ infinitely many solutions?
$(iii)$ a unique solution?

$x$ is larger in two numbers $x$ and $y$. Two times the larger number is $4$ more than five times the smaller number. The equation form of this data is $\ldots \ldots \ldots \ldots$