Write each of the following equations in the form $ax + by + c = 0$ and indicate the values of $a$, $b$ and $c$ in each case :

$(i)$ $2 x+3 y=4.37$

$(ii)$ $x-4=\sqrt{3} y$

$(iii)$ $4=5 x-3 y$

$(iv)$ $2 x=y$

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 $\rm {Rs.}$ $x$ and that of a pen to be $\rm {Rs.}$ $y$).

Given the point $(1,\, 2)$, find the equation of a line on which it lies. How many such equations are there ?

Give the equations of two lines passing through $(2, \,14)$. How many more such lines are there, and why ?

Write four solutions for equations : $\pi x+y=9$