CREATE TABLE table_name_50 (erp_w VARCHAR, class VARCHAR, call_sign VARCHAR)
SELECT erp_w FROM table_name_50 WHERE class = "a" AND call_sign = "wffc"
ERP W ใดมีคลาส A และมีสัญญาณเรียก wffc
Which ERP W has a Class of A, and a Call sign of wffc?