Diana used ⁵₇ of her white stickers and ³₇ of her purple stickers to decorate her diary. In the end, she had an equal number of white stickers and purple stickers left. Given that Diana had a total of 231 white and purple stickers at first, how many purple stickers did she use to decorate the diary?

	White stickers	Purple stickers
Before	7x2 = 14 u	7x1 = 7 u
Change	- 5x2 = - 10 u	- 3x1 = - 3 u
After	2x2 = 4 u	4x1 = 4 u

The number of white stickers and purple stickers in the end is the same.  Make the number of white stickers and purple stickers in the end the same.  LCM of 2 and 4 is 4.

Total number of stickers that Diana used to decorate the diary
= 14 u + 7 u
= 21 u

21 u = 231

1 u = 231 ÷ 21 = 11

Number of purple stickers that Diana used to decorate the diary
= 3 u
= 3 x 11
= 33

Answer(s): 33