Answer:
I'm going to write both of these because maybe you have a fill in the blank question. I don't know.

Simplify:

Step-by-step explanation:
is the equation of a circle with center (h,k) and radius r.
You are given (h,k)=(4,5) because that is the center.
You are given r=9 because it says radius 9.
Let's plug this in.

Simplify:

By flipping the fraction of -3/7, you will get the fraction of -7/3 or - 2 1/3.
Therefore, the reciprocal of -3/7 is - 2 1/3.
Hope this helps!
1800
20%=1/5 which means 360x5 is the number of people at the concert
360x5=1800
hope this helps :)