To find the rate of change, or slope, pick two points. The slope, is change in y coordinates over change in x coordinates. .
In this case, the slope is . Remember that subtracting a negative number equals adding the number without the negative sign. a-(-b) = a+b
Now for the y-intercept. The y-intercept is where the graph intersects the y-axis, where x = 0. You have the coordinate (0, -1), where x = 0. So the y-intercept is -1.
Putting these values into the slope-intercept form y = mx+b, the equation is y = -5x - 1