This is a linear (straight line) graph so you only need two points to graph it.
The ideal points are the intercepts.
The x-intercept is found by setting y=0: 5x+20=0, 5x=-20, x=-4 is the x-intercept.
The y-intercept is found by setting x=0: -y+20=0, y=20 is the y-intercept.
Draw a line through these intercepts, (0,20) and (-4,0). Arrange it so that the graph paper scales for each axis fit these points comfortably.
