SCHEMA:
CREATE TABLE table_name_5 (no_in_series INTEGER, written_by VARCHAR, no_in_season VARCHAR)
USER:
What is the sum of the numbers in series written by sam meikle, which have 21 numbers in the season?

QUERY:
SELECT SUM(no_in_series) FROM table_name_5 WHERE written_by = "sam meikle" AND no_in_season = 21