The numbers are how many seats the airline is willing to sell currently in that fare bucket, so if you want to know the total number of seats available you should look only at the highest bucket in each cabin. i.e. if a flight shows J6 C4 there are 6 total seats in biz that the airline is willing to sell at full J but they are only willing to make 4 of them available for a C fare. Similarly for Y and the lower economy buckets.

However, inventory is only shown up to 9, so if you see 9, that means "9 or more". So in this case there are at least 9 seats in biz and at least 9 in economy. Although again, this is how many the airline is willing to sell and may include overbooking so the true number of seats could be lower.