Capability Check: Compute survey score where some questions might be NA

Hi experts

My client has a customer survey which has 10 questions. For each question, there are 1 to 5 answers which has a score of 1 to 5 respectively. Furthermore, for each question, a "Not Applicable" option is also provided. My client requires the following scenarios:

1. If no NA answer then compute total score normally. Such that if all questions has "5" as score then: 5(score)x10(no. of questions)=50(total score); 50/50(maximum total score)=100%

2. If one question has NA as answer then C4C should only consider the 9 remaining scores. Such that if all questions has "5" as score then: 5x9=45; 45/45=100%. If the NA option is considered as score "0" then the total score will be wrong such that: (0+5+5+5+5+5+5+5+5+5)=45; 45/50=90%. Setting a question to NA meant the question shouldn't be considered.

I was able to create a simple custom report for scenario 1. But for scenario 2, is there any way this can be done? Help.

Thanks