Among all the players that are right-shooted, how many of them weigh over 90 kg?
right-shooted refers to shoots = 'R'; weigh over 90 kg refers to weight_in_kg > 90;
SELECT COUNT(T1.ELITEID) FROM PlayerInfo AS T1 INNER JOIN weight_info AS T2 ON T1.weight = T2.weight_id WHERE T2.weight_in_kg > 90 AND T1.shoots = 'R'