Answer:
y=-1/4x-1
How to find the slope
To find the slope of the line you need to do the change in y/change in x. This is also known as the rise/run. To do this you count the spaces in between the two points.
In this graph the change in y (rise) is 2. The change in x (run) is 8. Since the line is going down they are negative. The rise/run is -2/8. This can be simplified to -1/4.
Slope: -1/4x
How to find the y-intercept
To find the y-intercept, you need to look at where the line crosses y.
In this graph the line crosses y at -1.
Y-intercept: -1
Final equation: -1/4x-1