Answer:
See below.
Step-by-step explanation:
Recall the equation for a circle:
, where (h,k) is the center and r is the radius.
We need to turn the given equation into the above format. We do this by completing the square.
First, group them:

For the first section, complete the square for
:


Do the same for the second:



All together:



The center is (-9,-7).
The radius is 
Bob paid $48.6 that’s the total
Answer:
Do you mean which equation should the 5x+10=15 be multiplied to?
it would be -2
Step-by-step explanation:
This is because 5 times -2 is -10
and so when you add the (now) x value of the first equation to the x value of the second equation, it gets 0
which makes it eliminated!
-10x+10x=0