CREATE TABLE table_75557 ("Call sign" TEXT, "Frequency MHz" FLOAT, "City of license" TEXT, "ERP W" FLOAT, "Height m  (  ft  ) " TEXT, "FCC info" TEXT)

What is the number of Frequency MHz in woodstock, georgia?
SELECT SUM("Frequency MHz") FROM table_75557 WHERE "City of license" = 'woodstock, georgia'
SELECT SUM("Frequency MHz") FROM "table_75557" WHERE "City of license" = 'woodstock, georgia'