Answer:
Step-by-step explanation:
(x₁, y₁) = (19 , -4) & (x₂ ,y₂) = (17, -20)

![= \frac{-20-[-4]}{17-19}\\\\= \frac{-20+4}{17-19}\\\\= \frac{-16}{-2}\\\\= 8](https://tex.z-dn.net/?f=%3D%20%5Cfrac%7B-20-%5B-4%5D%7D%7B17-19%7D%5C%5C%5C%5C%3D%20%5Cfrac%7B-20%2B4%7D%7B17-19%7D%5C%5C%5C%5C%3D%20%5Cfrac%7B-16%7D%7B-2%7D%5C%5C%5C%5C%3D%208)
m = 8
Parallel lines have same slope.
Parallel slope = 8
Slope of perpendicular line = 
Perpendicular slope = 
Finding the mean is you have to add it all up:
49+55+52+46+47+42+38= 328
The divide it by the amount of numbers so, 329/7= 47.
Subtract 47 from every number then, but even if you get a negative number you gotta keep it a positive so just ignore it if you get a negative answer when subtracting, once you do that you would add up those answers you got so;
2+8+5+1+0+5+9= 30
Then divide it again, 30/7
Which then you get the M.A.D which is 4.3, rounded to the nearest ten.
<span>is is 42 ok but try to see why and study =)</span>
So i think in the school there may be 4800 in the school. Hope this helps