Esther and Shiyun had a total of 40 stamps. Shiyun gave ¹₆ of her stamps to Esther. In return, Esther gave ¹₅ of the total number of stamps that she had to Shiyun. In the end, each girl had the same number of stamps. How many stamps did Esther have at first?

	Esther	Shiyun	Total
Before 1	?	6 u	40
Change 1	+ 1 u	- 1 u
After 1	25	5 u	40
Before 2	5 p	5 u	40
Change 2	- 1 p	+ 1 p
After 2	4 p (20)	20	40

Since Shiyun gave some stamps to Esther and Esther then gave some stamps to Shiyun, it is an internal transfer of stamps between the two girls. So, the total number of stamps remains unchanged.

Number of stamps that Shiyun and Esther each had in the end is the same.

Number of stamps that Esther had in the end
= 40 ÷ 2
= 20

Number of stamps that Esther had in the end = 4 p

4 p = 20

1 p = 20 ÷ 4 = 5

Number of stamps that Esther had after receiving some stamps from Shiyun
= 5 p
= 5 x 5
= 25

Number of stamps that Shiyun had after giving to Esther
= 40 - 25
= 15

5 u = 15

1 u = 15 ÷ 5 = 3

Number of stamps that Shiyun had at first
= 6 u
= 6 x 3
= 18

Number of stamps that Esther had at first
= 40 - 18
= 22

Answer(s): 22