CREATE TABLE table_77615 ("Call sign" TEXT, "Frequency MHz" TEXT, "City of license" TEXT, "ERP W" FLOAT, "Class" TEXT, "FCC info" TEXT)

Name the frequence MHz for ERP W of 55
SELECT "Frequency MHz" FROM table_77615 WHERE "ERP W" = '55'
SELECT "Frequency MHz" FROM "table_77615" WHERE "ERP W" = '55'