CREATE TABLE table_77580 ("Entrant" TEXT, "Constructor" TEXT, "Chassis" TEXT, "Engine \\u2020" TEXT, "Tyre" TEXT, "Driver" TEXT, "Rounds" TEXT)

what is the rounds when the engine is mercedes fo110m?
SELECT "Rounds" FROM table_77580 WHERE "Engine \u2020" = 'mercedes fo110m'
SELECT "Rounds" FROM "table_77580" WHERE "Engine \u2020" = 'mercedes fo110m'