Not a bad first attempt. Note that the line crosses the yaxis when x=0 i.e. y=510. That is 1/10th of the way between 500 and 600. So you could be more accurate.
You could label you axes and label you functions along with the start and end point i.e the domain of x. If they are are infinite extend them to fill the whole of the graph area i.e for negative x.
You should be able to solve the simultaneous equations to get the point of intersection's coordinates.
