There was an equal number of chairs and benches in the morning. At 2 p.m., some chairs were added and some benches were removed, resulting in the number of chairs being increased by 20% while the number of benches decreased by 30%. At 5 p.m. the number of chairs increased by 50%. If a total of 80 chairs were added during the day, how many more chairs than benches were there in the end?

At 2 p.m.	Chairs	Benches
Before	1 u	1 u
Change	+ 0.2 u	- 0.3 u
After	1.2 u	0.7 u

At 5 p.m.	Chairs	Benches
Before	1.2 u	0.7 u
Change	+ 0.6 u	No change
After	1.8 u	0.7 u

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

Number of benches removed
= 30% x 1 u 
= ³⁰₁₀₀ x 1 u
= 0.3 u

Number of chairs increased by chairs at 5 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 = 80

1 u = 80 ÷ 0.8 = 100

Number of more chairs than benches in the end
= 1.8 u - 0.7 u
= 1.1 u
= 1.1 x 100
= 110

Answer(s): 110