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 (fa_cup_goals INTEGER, league_goals VARCHAR, club VARCHAR)

### Question ###
Which FA Cup goals have a League goals of 18, and a Club of sheffield united?

### Accurate SQL ###

SELECT MAX(fa_cup_goals) FROM table_name_20 WHERE league_goals = "18" AND club = "sheffield united"