In one

There are 13 spines and 7 entrances in a panel house. In each entrance, there are 2 three-room and 1 two-room apartments in each of the nine spines, and in the remaining four floors, there are always 1 four-room and 2 two-room apartments on each floor. Calculate how many apartments there are in this house in total and how many of them are four-room, three-room, and two-room.

Final Answer:

t =  273
a =  28
b =  126
c =  119

Step-by-step explanation:

$$\begin{gathered} n=7 \\ a=n\cdot (4\cdot 1)=7\cdot (4\cdot 1)=28 \\ b=n\cdot (9\cdot 2)=7\cdot (9\cdot 2)=126 \\ c=n\cdot (9\cdot 1+4\cdot 2)=7\cdot (9\cdot 1+4\cdot 2)=119 \\ t=a+b+c=28+126+119=273 \end{gathered}$$

Try another example