Try this solution:
1. In order to built the line required in the condition it need to determine its equation.
Using the coordinates of point B (5;2), if to substitute them into the given equation: 2=-3*5+b, ⇒ b=17. It means, that the equation of the line required in the condition is y= -3x+17.
2. The graph is in the attachment; point (0;17) is the intersection point of Y-axis and the line.
