I found your complete question in another source.
See attached image.
For this case what you should see is that you have two similar triangles.
We then have the following relationship:
((AB) / (BX)) = ((CD) / (DX))
We cleared CD:
CD = ((AB) / (BX)) * (DX)
Substituting the values:
CD = ((12) / (5)) * (2.5)
CD = 6
Answer:
CD = 6
Slope is 
Look at the image below. The rise is labeled in green and the run in pink
In this case the rise is 3 and run is 1
The slope is

OR
3
Hope this helped!
~Just a girl in love with Shawn Mendes
Answer:
(x + 7)² + (y - 8)² = 49
Step-by-step explanation:
Circle Equation: (x - h)² + (y - k)² = r²
(h, k) is center
<em>r</em> is radius
Step 1: Define
h = -7
k = 8
r = 7
Step 2: Substitute
(x - -7)² + (y - 8)² = 7²
(x + 7)² + (y - 8)² = 49
It’s the last one because that one has no repeats. One outcome can not be listed twice