user: 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?
Columns: ['Player', 'Club', 'League', 'Play-offs', 'FA Cup', 'FA Trophy', 'Total']
Types: ['text', 'text', 'real', 'real', 'real', 'real', 'real']
Sample row: ['Stuart Fleetwood', 'Forest Green Rovers', 28.0, 0.0, 6.0, 2.0, 36.0]
SQL:

assistant: SELECT AVG("Play-offs") FROM "Table" WHERE "League" > 18.0 AND "Player" = 'john grant' AND "Total" > 25.0;