To get to the city centre you catch a bus (which is free) from outside the hotel to the main metro line, then take a subway to the main centre. (loveholidays.com)
With an open jaw, you are free to get to the city from which you will depart however you choose. (straighttothepoints.co)
Getting to the city center in Pest takes about 10 to 15 minutes by public transport. (visitbudapest.travel)