Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_20 ( ast_avg INTEGER, rank VARCHAR, games VARCHAR )

### Question ###
WHAT IS THE SUM OF AST AVG WITH RANK 5 AND GAMES BIGGER THAN 108?

### Accurate SQL ###

SELECT SUM(ast_avg) FROM table_name_20 WHERE rank = 5 AND games > 108