The cost of a notebook is twice the cost of a pen. Write a linear equation in two variables to represent this statement. (Take the cost of a notebook to be Rs. $x$ and that of a pen to be Rs. $y$).

If the work done by a body on application of a constant force is directly proportional to the distance travelled by the body,express this in the form of an equation in two variables and draw the graph of the same by taking the constant force as $5$ units. Also,read from the graph the work done when the distance travelled by the body is:
$(i)$ $2$ units
$(ii)$ $0$ units

Express the following linear equation in the form $ax + by + c = 0$ and indicate the values of $a$,$b$,and $c$: $2x = -5y$.

The graph of the equation $3x = 10$ is parallel to which axis?

Express the following linear equation in the form $ax + by + c = 0$ and indicate the values of $a, b$ and $c$ in each case:
$2y - 3x = 14$

Write the following as an equation in two variables:
$\pi x = 3.14$