Your codes are incorrect. Please refer this to do the correction
If still not understanding, let me know
Note: Please stop copy and pasting your code that is when you do most of the mistake, why have you written double times most of the code with = sign??
Your C2 Code cell looks like this and you have taken the hint part of the code and pasted in your grader cell and that is why you are stuck
Hints are only to help you get the right code which you apply accordingly and do not copy and paste as shown in the hint cells.
Regards
DP