Answer:
B
Step-by-step explanation:
Step-by-step explanation:
To calculate a slope, we need to apply: 
Applying formula to each slope:

So, as you can see, there are equal pair of slopes, meaning that they are parallels, which<em> demonstrate that it's actually a quadrilateral figure.</em>
99 because anything less will give you an average of 89 and a decimal
We can let
a = 1/(x-1)
b = 1/(y+2)
and rewrite the equations as
2a - b = 10
a + 3b = -9
Using the first to write an expression for b, we get
b = 2a - 10
Substituting this into the second equation gives
a + 3(2a -10) = -9
7a -30 = -9 . . . . . . . . simplify
7a = 21 . . . . . . . . . . .add 30
a = 3
b = 2·3 - 10 = -4
Now, we can find x and y.
3 = 1/(x -1)
x - 1 = 1/3
x = 1 1/3 = 4/3
-4 = 1/(y +2)
y +2 = -1/4
y = -2 1/4 = -9/4
Then the desired sum is
x + y = 4/3 -9/4 = (16 -27)/12
x + y = -11/12
The appropriate choice is ..
c. -11/12
If I understand what you are asking, you can use the median as an average since it is not affected by the mean ( median is a measure of center). Since a mean is affected by outliers, it might lower the score if there are very low outliers. But note that if there are outliers way <em>greater </em>it can increase the average. You can use the Inter Quartile Range if shown on a box plot ( measure of variability).