Breaking competencies calculation on competence template in average and sum

Hi,

I have a requirement from client to calculate competencies on the basis of their type. Following is the detail.

Client has 10 competencies which are divided into 2 types General competencies and  functional competencies as follows

1. A.General. Competency - 1

2. A.General. Competency - 2

3. A.General. Competency - 3

4. A.General. Competency - 4

5. A.General. Competency - 5

6. B.Functional. Competency - 6

7. B.Functional. Competency - 7

8. B.Functional. Competency -8

9. B. Functional. Competency -9

10 B. Functional. Competency -10

Now my client requirement is to calculate "General Competencies"  on average basis like sum ratings of general competencies and divide the sum by 5 (total number of general competencies) and then divide by 2 as general competencies are 50% of general + functional competencies. And .... calculate "Functional Competencies" on sum basis like providing weightage against each functional ratings (Performance x weightage)  and sum of  line score of functional competencies. So finally     Total Rating = General + Functional competencies.