I believe it's graph C! I hope it will help you...
Answer:
Ammm, I think the answer you have is wrong, but what I really think is that the equations you put in are not the right ones because the answer for these is "ugly" (decimals etc...). Want to check your equations?
Step-by-step explanation:
Here is a step by step explanation to your equations (I assumed +3z for the second but you can change it). You can edit it for your equations if you want to.
https://simplisico.com/share/q/QiWKOyN5uYgkSG4iBXOmdG0i
Answer:

Step-by-step explanation:
add all qestions together 10+3+9=22
and put the number of free responces on top of the total number of qestions

and you cant simplify it so its in its simplist form