$x=-1$ and $y=-2$ is one of the solutions of the equation $\ldots \ldots \ldots \ldots$

Obtain the solution of the following pair of equations by elimination method:
$\frac{11}{y} - \frac{7}{x} = 1, \, \frac{9}{y} - \frac{4}{x} = 6$; $x \neq 0, \, y \neq 0$

Ankita travels $14 \,km$ to her home partly by rickshaw and partly by bus. She takes half an $hour$ if she travels $2 \,km$ by rickshaw and the remaining distance by bus. On the other hand,if she travels $4 \,km$ by rickshaw and the remaining distance by bus,she takes $9 \,minutes$ longer. Find the speed of the rickshaw and of the bus (in $km/h$).

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

Solve the following pair of linear equations using a graph: $3x + 4y = 6$ and $3x + 4y = 19$.

Solve the following pairs of linear equations: $\frac{2}{x} + \frac{3}{y} = \frac{9}{xy}, \quad \frac{4}{x} + \frac{9}{y} = \frac{21}{xy} \quad (x \neq 0, y \neq 0)$