Draw the graph of the equation represented by a straight line which is parallel to the $x$-axis and at a distance of $3$ units below it.

State whether the following statement is True or False. Justify your answer:
The graph of every linear equation in two variables need not be a line.

The total cost of a school picnic consists of two parts: a fixed bus fare of ₹ $200$ and the cost of snacks at the rate of ₹ $30$ per student. Representing the total number of students by $x$ and the total cost by $y$,form a linear equation in two variables. If the number of students going on the picnic is $40$,find the total cost.

Let $y$ vary directly as $x$. If $y=12$ when $x=4$,then write a linear equation. What is the value of $y$ when $x=5$?

The total cost of $3$ sweetlimes and $6$ oranges is ₹ $210$. Show this statement as a linear equation in two variables.

Draw the graph of the equation represented by a straight line which is parallel to the $x$-axis and at a distance $3$ units below it.