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>

Step-by-step explanation:
ofc , so that is that and the other is that
Here're the answers!!! Good luck!!
1) a = -7 (The first picture -Left to right)
2) x = -39
3) a = -2.1 (The last picture left to right)
Hoping this helped you out!! If my answer best helped you, please mark Brainliest! ;)
9 : 2 = 18 : 4
As: 9 x 2 : 2 x 2 = 18 : 4
--------------------
36 : 8 = 18 : 4
As: 18 x 2 : 4 x 2 = 36 : 8
--------------------
72 : 16 = 18 : 4
As: 18 x 4 : 4 x 4 = 72 : 16