There are 85 stickers in Container Y and 65 stickers in Container Z.
Some stickers are transferred from Container Y to Container Z.
Container Z has 40 more stickers than Container Y.
How many stickers are transferred from Container Y to Container Z?

	Container Y	Container Z
Before	85	65
Change	- ?	+ ?
After	1 u	1 u + 40

Total number of stickers
= 85 + 65
= 150

In the end
Total number of stickers = 1 u + 1 u + 40 = 2 u + 40

The total number of stickers at first and in the end remains unchanged.

2 u + 40 = 150
2 u = 150 - 40 = 110

1 u = 110 ÷ 2 = 55

Number of stickers that are transferred from Container Y to Container Z
= Number of stickers in Container Y at first - Number of stickers in Container Y in the end
= 85 - 55
= 30

Answer(s): 30