Answer:
Apartment 207 is a second floor apartment in Building 2.
Explanation:
Since one building has four first floor apartments, then I'd think all buildings have 4 apartments per floor. Since one building has first floor apartment numbers 109, 110, 111, and 112, then I'd think there is a building with first floor apartment numbers 101, 102, 103, and 104, and another building with first floor apartment numbers 105, 106, 107, 108.
Building 1 First floor: 101, 102, 103, 104
Building 2 First floor: 105, 106, 107, 108
Building 3 First floor: 109, 110, 111, 112
Building 2 Second floor: 205, 206, 207, 208
Apartment 207 is a second floor apartment in Building 2.