=SUMPRODUCT((A$2:A$100>DATE(YEAR(NOW()),MONTH(NOW())-1,DAY(NOW())))*(B$2:B$100=G2)*E$2:E$100)/SUMPRODUCT((A$2:A$100>DATE(YEAR(NOW()),MONTH(NOW())-1,DAY(NOW())))*(B$2:B$100=G2)*C$2:C$100)
