### Theory:

What is a linear equation in two variable?

A linear equation in which two variables are involved in which each variable is in the first degree.

It can be written in the form of $$ax+by+c = 0$$ where $$a$$, $$b$$ and $$c$$ are real numbers, both $$a$$ and $$b$$ are not equal to zero, $$x$$ and $$y$$ are variables and $$c$$ is a constant.
The equation in which two variables involved, each of which is in the first degree. These variables are arranged so that they are not multiplied by each other is called a linear equation in two variables.
Example:
$$x+y = 2$$, $$x+2y = 6$$, $$3x = 9y$$, $$-2y+\frac{1}{4} = 4x$$
These equations are called as linear equations in two variables.