The length should be 80 feet.
This is because the width is 20 since there are two sides for the width in pen, we have to add 20+20. This would equal 40. Then we need to subtract 40 from 200. 200-40 would be 160. Then since there are two sides for the length, we need to split that in half. 160÷2 would be 80. To double check, you can do 80+80, and that would still be 160. So the length of one side would be 80. But of course, this whole thing would only be right if the pen has four sides(but since I have seen many chicken pens, there were all rectangular)
Let
x--------> the number of sessions
y-------> the total payment
we know that
without membership:
--------> equation 
with membership:
--------> equation 
using a graph tool------> resolve the system of equations
see the attached figure
the solution is the point 
that means
For 
the cost is
in both forms
so
to justify buying the membership

therefore
<u>the answer is</u>

First note that

If you take limit, then you have
Hello from MrBillDoesMath!
Answer:
1^3 = 1
2^3 = 8
3^3 = 27
4^3 = 64
5^3 = 125
6^3 = 216
7^3 = 343
8^3 = 512
9^3 = 729
10^3 = 1000
Thank you,
MrB