If you're looking for the cartesian form of this straight line then that would be,
If you're looking for the equation in the form of y=mx+b, then:
Where -3/2 is the slope of the line
and 4 is the intersection with the y-axis (0,4)
if you want to graph this line, just take values of x and find their y, and plot these points.
finally join the points to get the graph of the line.
hope this clears things up