Answer:
m=-7
Step-by-step explanation:
The slope intercept form is y=mx+b.
So, the variable that represents slope is x.
If your plug your equation in, -7 would be the slope.
Answer:
16 + n
Step-by-step explanation:
Increased is addition
For this case we have by definition that the area of a parallelogram is given by:

Where:
b: It's the base
h: It's the height
According to the data we have:

Substituting in the formula:

The area of the parallelogram is 
Answer:

The box and whisker plot is attached.
We first order the data from least to greatest:
6, 7, 11, 13, 14, 15, 15, 19, 21
The median is the middle value, or 14.
The lower quartile is the median of the lower half (split by the median). This is between 7 and 11: (7+11)/2 = 18/2 = 9
The upper quartile is the median of the upper half (split by the median). This is between 15 and 19: (15+19)/2 = 34/2 = 17
The highest value is 21.
The lowest value is 6.
We draw the middle line of the box at 14, the median. We draw the left side of the box at the lower quartile, 9. We draw the right side of the box at the upper quartile, 17. From the right side of the box, we draw a whisker to the highest value, 21. From the left side of the box, we draw a whisker to the lowest value, 6.
I think that using the elimination method is the best, because it is the only method that I use when solving these types of equation. For example, for these two equations, you need to multiply one of the equations by a certain number so that you'd be able to find x and y. The elimination method is the method that tells you to do that. It is also the easiest method.
~Hope I helped!~