How many games were sold on the DS platform on average in the 4 different regions?
on the DS platform refers to platform_name = 'DS'; number of games sold on average = divide(sum(multiply(num_sales, 100000)), 4) where platform_name = 'DS'
SELECT SUM(T1.num_sales) * 100000 / 4 FROM region_sales AS T1 INNER JOIN game_platform AS T2 ON T1.game_platform_id = T2.id INNER JOIN platform AS T3 ON T2.platform_id = T3.id WHERE T3.platform_name = 'DS'