user: Question: What is the sum of the numbers in series written by Sam Meikle, which have 21 numbers in the season?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Ratings']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [377.0, 1.0, '"Family Matters"', 'Kevin Carlin', 'Louise Crane-Bowes', '13February2007', '1.081']
SQL:

assistant: SELECT SUM("No. in series") FROM "Table" WHERE "Written by" = 'Sam Meikle' AND "No. in season" = 21.0;