slope = (change in y) / (change in x)
In this case... the change in y = -1 the change in x = 5
for the y axis minus is down and plus is up for the x axis minus is left and plus is right
so place one point anywhere on the graph and then go down 1 and right 5 and place a second point on the graph. Draw a line throught the two points.
Extra - it doesn't matter if you start with the x value first or the y value first. You will end up at the same place :-)