human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Player, Club, League, Play-offs, FA Cup, FA Trophy, Total
###Question: What is the mean number of play-offs when the league number was bigger than 18, where the player was John Grant and the total number was bigger than 25?
gpt
SELECT AVG Play-offs FROM table WHERE League > 18 AND Player = john grant AND Total > 25