CREATE TABLE table_name_42 (weight__kg_ VARCHAR, race VARCHAR)
What was the combined weight in kilograms of the horses in the race at Chelmsford stakes?
SELECT COUNT(weight__kg_) FROM table_name_42 WHERE race = "chelmsford stakes"
SELECT SUM(CAST(weight__kg_ AS FLOAT)) AS combined_weight
FROM table_name_42
WHERE race = 'Chelmsford stakes';