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

	Silver stickers	Yellow 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 silver stickers and yellow stickers in the end is the same.  Make the number of silver stickers and yellow stickers in the end the same.  LCM of 2 and 4 is 4.

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

21 u = 231

1 u = 231 ÷ 21 = 11

Number of yellow stickers that Kathy used to decorate the diary
= 3 u
= 3 x 11
= 33

Answer(s): 33