In order to do this, we need the general equation of a line which is y=mx+c (where m is the gradient and c is the y-intercept or the value when x is 0)
In this example, the value of m is 1/2 and the value of c is -3/2 because it is the value of y when x is 0.
Therefore the equation of the line is y=(1/2)x-3/2
We can tidy this up a bit to 2y=x-3