ANSWER:
y=-x-1
EXPLANATION:
First you need to find the slope of the points (-1,0) and (4,-5). To find the slope you use the equation m=y2-y1/x2-x1
-5=y2
0=y1
4=x2
-1=x1
So, plugging the numbers into the equation, you should get m=-5-0/4-(-1)
Then you get -5/5 which simplifies to -1
Since slope intercept form is y=Mx+B, m=slope, you substitute -1 into the m spot.
To find the y-intercept, you need to first pick one of the points to use. (I will use (4,-5))
The 4 is in the x position in (x,y) so you plug that into the equation. y=-1(4)+b
The -5 is in the y position in (x,y) so you have to plug that into the equation as well. -5=-1(4)+b
Simplified you get -5=-4+b
You then have to add 4 to both side of the equation, which ends you up with -1=b. b is the y intercept so when you plug every thing into the equation you get y=-x-1
Hope that helps!