At the office building, Floor L and Floor M had an equal number of chairs at first. If 9 chairs were removed from Floor M and 3 times as many chairs were removed from Floor L as Floor M, the number of chairs in Floor M would be 3 times as many as in Floor L. Find the number of chairs on each floor.

	Floor L	Floor M
Before	1 u	1 u
Change	- 27	- 9
After	1 u - 27	1 u - 9

Number of chairs removed from Floor L
= 3 x 9
= 27

Number of chairs on Floor L and Floor M at first is the same.

Number of chairs on Floor M is 3 times as many as Floor L in the end. If the number of chairs on Floor L increases by 3 times, the number of chairs on Floor L and Floor M will be the same.

3(1 u - 27) = 1 u - 9
3 u - 81 = 1 u - 9 
3 u - 1 u = 81 - 9
2 u = 72

1 u = 72 ÷ 2 = 36

Number of chairs in each floor
= 1 u
= 36

Answer(s): 36