Ajit lives on the 18th floor of a building. He came down 9 floors and collected his Maths textbook from his friend Karan. Later, he went up along with Karan to Goutham's house which is 12 floors above Karan's for group work. If Goutham lives on the topmost floor of the building, how many floors does the building have?
21
Since Ajit came down 9 floors from 18th floor to meet Karan,
Karan lives on the (18 - 9) = 9th floor.
Goutham's house is 12 floors above Karan's house.
Goutham lives on (9 + 12)th floor
= 21th floor.
Therefore, the building has 21 floors.