Krystiana owns an apartment building. The rooms on the first floor cost $15 per month and the rooms on the 2nd floor cost $20 per month. The rooms on the third floor cost twice as much as the rooms on the first floor, but only two rooms are occupied. If each floor has 3 rooms, how much does Krystiana earn every month? Let's be accurate as possible.
Krystiana earns $15 x 3 = $45 for the rooms on the first floor every month. She earns $20 x 3 = $60 for the rooms on the second floor every month. And the cost for each room on the third floor is $15 x 2 = $30. So, the total amount she earns for the rooms on the third floor is $30 x 2 = $60 every month. Therefore, the total amount she earns from the apartment building is $60 + $60 + $45 = $165.
The answer: 165.