weighted average

Thanks for my previous help. Now I have the data and I need to do a weighted
average for different groups of data as follows:

group 1:
Total count 3 total count 23 total count 12
12 9 5
2 7 3
5 8 1

Group 2 has same heading as above but more rows of data:
2 7 1
3 6 1
2 3 1
6 5 1
6 5 1


I have 8 separate groups.

Once again appreciate your help.