To find the slope, find two points that are centred exactly on the crosshairs of the grid. In this case, I chose (0, -4) and (5, 4). The slope, m, is rise/run. To get from (0, -4) to (5, 4), you need to go up 8 units and right 5 units.
The slope is: 8/5
To find the y-intercept, look at the point on the y-axis.
The y-intercept is: -4
If you were to graph the equation y = (8/5)x - 4, you get the same linear graph.