My calculation is roughly that the total area is two times the sum of the area of living room and the area of the bigger bedroom:
(13*17+10.5*15)*2 = 757.0 (sq Ft).
However it shows the apartment is approximately 905 sq Ft, which is about 150 sq Ft larger than my calculation, i.e. almost the size of the bigger bedroom. So I wonder where there is such a big difference? Is this common for apartments and houses?