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_30 ( tries_against VARCHAR, try_diff VARCHAR, points_for VARCHAR )

### Question ###
How many Tries against has a Try diff of 17 and Points for smaller than 80?

### Accurate SQL ###

SELECT COUNT(tries_against) FROM table_name_30 WHERE try_diff = "–17" AND points_for < 80