There are 90 stickers in Container P and 90 stickers in Container Q.
Some stickers are transferred from Container P to Container Q.
Container Q has 90 more stickers than Container P.
How many stickers are transferred from Container P to Container Q?

	Container P	Container Q
Before	90	90
Change	- ?	+ ?
After	1 u	1 u + 90

Total number of stickers
= 90 + 90
= 180

In the end
Total number of stickers = 1 u + 1 u + 90 = 2 u + 90

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

2 u + 90 = 180
2 u = 180 - 90 = 90

1 u = 90 ÷ 2 = 45

Number of stickers that are transferred from Container P to Container Q
= Number of stickers in Container P at first - Number of stickers in Container P in the end
= 90 - 45
= 45

Answer(s): 45