There was an equal number of chairs and stools in the morning. At 4 p.m., some chairs were added and some stools were removed, resulting in the number of chairs being increased by 20% while the number of stools decreased by 20%. At 10 p.m. the number of chairs increased by 50%. If a total of 36 chairs were added during the day, how many more chairs than stools were there in the end?

At 4 p.m.	Chairs	Stools
Before	1 u	1 u
Change	+ 0.2 u	- 0.2 u
After	1.2 u	0.8 u

At 10 p.m.	Chairs	Stools
Before	1.2 u	0.8 u
Change	+ 0.6 u	No change
After	1.8 u	0.8 u

Number of chairs added
= 20% x 1 u
= ²⁰₁₀₀ x 1 u
= 0.2 u

Number of stools removed
= 20% x 1 u 
= ²⁰₁₀₀ x 1 u
= 0.2 u

Number of chairs increased by chairs at 10 p.m.
= 50% x 1.2 u
= ⁵⁰₁₀₀ x 1.2 u
= 0.6 u

Number of chairs added during the day
= 1.8 u - 1 u
= 0.8 u

0.8 u = 36

1 u = 36 ÷ 0.8 = 45

Number of more chairs than stools in the end
= 1.8 u - 0.8 u
= 1 u
= 1 x 45
= 45

Answer(s): 45