If $(x, -1)$ is the solution of the linear equation of two variables $3x - y = 7$,then $x = \ldots$

Find the value$(s)$ of $p$ for the equations $-3x + 5y = 7$ and $2px - 3y = 1$ if the lines represented by these equations intersect at a unique point.

Which of the following groups matches the data of Part $I$ with the data of Part $II$?

Part $I$	Part $II$
$1. x+2y=3, 2x+4y=5$	$a. \text{Solution set is a singleton set.}$
$2. 2x+3y=6, x+\frac{3}{2}y=3$	$b. \text{Solution set is an empty set.}$
$3. 3x-y=0, x-y+6=0$	$c. \text{Solution set is an infinite set.}$
	$d. \text{Solution set contains two members.}$

In $\Delta ABC$,$m \angle A = x$,$m \angle B = 3x$,and $m \angle C = y$. If $3y - 5x = 30$,show that the triangle is right-angled and find the measures of all three angles.

Solve the following pair of linear equations by the cross-multiplication method:
$\frac{x}{a} + \frac{y}{b} = 0$
$(a+b)x + (a-b)y = a^2 + b^2$

On comparing the ratios $\frac{a_{1}}{a_{2}}, \frac{b_{1}}{b_{2}}$ and $\frac{c_{1}}{c_{2}}$,find out whether the following pair of linear equations are consistent or inconsistent:
$\frac{4}{3} x + 2 y = 8$; $2 x + 3 y = 12$