password? im not understanding this

[helpmeplz2]

so i have this "password" for marble mansion from the math puzzle 3x879+453=3090,but i dont get what im supposed to do with it,i even opened the apartment yuou use the key for,and nothing in the mansion changed,so what do i do???????????

[WSGreen]

Go to the top floor of the mansion and use the pc there and enter the password in there