SQL SUM Values need and then AVG of 2 Tables

From this it is possible for the following :

   TABLE 1
   Id | final | Date
   ------------------
    1    236    02-11-14
    2     10    07-01-12
    3     58    09-02-10

   TABLE 2
   Id | final | Date
 ------------------
   1     330    02-11-14
   2     5      07-01-12
   3     100    09-02-10

ADD both Table 1 and Table 2 Sum'd values, and then work out the AVG number from this and create this as another column average, THEN if table2 for example SUM'd original amount (before the AVG) is higher than Table 1 SUM'd amount create another column and print in that column 'Tbl2 has the higher amount' and vise verser if table 1 had the higher amount.

End result Column wise table would look like this :

  ID|date|tb1_final_amount|tb2_final_amount|Avg_Amount|Top_Score_tbl