Find the value of $k$ if $(5, 2)$ is a solution of $3x + ky = 25$.

Determine the point on the graph of the equation $2x + 5y = 20$ whose $x$-coordinate is $\frac{5}{2}$ times its ordinate.

If the point $(3, 5)$ lies on the graph of the equation $ax + y = 20$,find the value of $a$.

Write whether the following statement is True or False? Justify your answer.
The coordinates of points given in the table:

$x$	$0$	$1$	$2$	$3$	$4$
$y$	$2$	$4$	$6$	$8$	$10$

represent some of the solutions of the equation $2x + 2 = y$.

Draw the graph of the equation represented by the straight line which is parallel to the $x$-axis and is $4$ units above it.

If $(2,3)$ is a solution of the equation $7x - 3y = a$ and $(a, a+1)$ is a solution of the equation $2x + y = b$,find the values of $a$ and $b$.