What is the percentage difference of River City sale compare to Frostie?
percentage difference = (DIVIDE(MULTIPLY(SUBTRACT(SUM(PurchasePrice WHERE BrandName = 'River City'), SUM(PurchasePrice WHERE BrandName = 'Frostie')), 100), SUM(PurchasePrice WHERE BrandName = 'Frostie'))); River City refers to BrandName = 'River City'; Frostie refers to BrandName = 'Frostie';
SELECT CAST((SUM(CASE WHEN T3.BrandName = 'River City' THEN T2.PurchasePrice ELSE 0 END) - SUM(CASE WHEN T3.BrandName = 'Frostie' THEN T2.PurchasePrice ELSE 0 END)) AS REAL) * 100 / SUM(CASE WHEN T3.BrandName = 'Frostie' THEN T2.PurchasePrice ELSE 0 END) FROM rootbeer AS T1 INNER JOIN `transaction` AS T2 ON T1.RootBeerID = T2.RootBeerID INNER JOIN rootbeerbrand AS T3 ON T1.BrandID = T3.BrandID