Vincent and Julian had 70 stickers in total. Julian had 12 stickers more than Vincent at first. After Vincent and Julian played a game with Yen, Vincent had ²₅ as many stickers as Julian. If Vincent lost as many stickers as Julian to Yen, find the number of stickers that Vincent lost to Yen.

	Vincent	Julian	Difference
Before	1 u	1 u + 12	12
Change	- ?	- ?
After	2 p	5 p	3 p

Total number of stickers at first
= 1 u + 1 u + 12 
= 2 u + 12

2 u + 12 = 70
2 u = 70 - 12
2 u = 58

1 u = 58 ÷ 2 = 29

Since Vincent lost the same number of stickers as Julian, the difference in the number of stickers between Vincent and Julian at first and in the end remains the same.

Difference in the number of stickers in the end
= 5 p - 2 p
= 3 p

3 p = 12

1 p = 12 ÷ 3 = 4

Number of stickers that Vincent lost to Yen
= 1 u - 2 p
= 29 - 2 x 4
= 29 - 8
= 21

Answer(s): 21