Tim had to paint some containers. On the first day, the number of containers he painted was 20% of the number of containers that he had not painted. One week later, he painted another 28 containers. As a result, the total number of painted containers became 18 more than ¹₂ of the total number of containers. How many less containers were painted than unpainted on the first day?

	Painted	Not painted	Total
Before	1x1 = 1 u	5x1 = 5 u	6x1 = 6 u
Change	+ 28	- 28
After	1 u + 28	5 u - 28	6 u
Comparing painted and not painted containers in the end	1x3 + 18 = 3 u + 18	1x3 - 18 = 3 u - 18	2x3 = 6 u

20% = ²⁰₁₀₀ = ¹₅
Painted : Not painted = 1 : 5

The total number of containers remains unchanged. Make the total number of containers at first and in the end the same.  LCM of 6 and 2 is 6.

The number of containers painted in the end is repeated.

3 u + 18 = 1 u + 28
3 u - 1 u = 28 - 18
2 u = 10

1 u = 10 ÷ 2 = 5

Number of less containers that were painted than not painted on the first day
= 5 u - 1 u
= 4 u
= 4 x 5
= 20

Answer(s): 20