Among games sold in Europe, list the platform ID of games with sales lesser than 30% of the average number of sales.
Europe refers to region_name = 'Europe'; sales lesser than 30% of the average number of sales refers to SUM(num_sales) < MULTIPLY(AVG(num_sales), 0.3);
SELECT DISTINCT T3.platform_id FROM region AS T1 INNER JOIN region_sales AS T2 ON T1.id = T2.region_id INNER JOIN game_platform AS T3 ON T2.game_platform_id = T3.id WHERE T1.region_name = 'Europe' AND T2.num_sales * 100 * 100000 < ( SELECT AVG(T2.num_sales * 100000) * 30 FROM region AS T1 INNER JOIN region_sales AS T2 ON T1.id = T2.region_id WHERE T1.region_name = 'Europe' )