The two functions are 1st degree polynomial, so they are both lines.
In order to draw a line, you have to sample two points and connect them.
To sample points from an equation, choose any value for x and compute the correspondent value for y.
For example, if we choose x=0 and x=1 for the first equation, we have
So, the line passes through the points and
Similarly, if we choose x=0 and x=3 for the first equation, we have
So, this line passes through the points and
If you draw the two points for each line and connect the pairs, you'll have the two lines.