Write SQL query to solve given problem: For those objects that have multiple relations, how many images have a prediction class of "reading"?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(T1.IMG_ID) FROM IMG_REL AS T1 INNER JOIN PRED_CLASSES AS T2 ON T1.PRED_CLASS_ID = T2.PRED_CLASS_ID WHERE T2.PRED_CLASS = 'reading'