Barbara used ²₅ of her white stickers and ²₇ of her black stickers to decorate her diary. In the end, she had an equal number of white stickers and black stickers left. Given that Barbara had a total of 460 white and black stickers at first, how many black stickers did she use to decorate the diary?

	White stickers	Black stickers
Before	5x5 = 25 u	7x3 = 21 u
Change	- 2x5 = - 10 u	- 2x3 = - 6 u
After	3x5 = 15 u	5x3 = 15 u

The number of white stickers and black stickers in the end is the same.  Make the number of white stickers and black stickers in the end the same.  LCM of 3 and 5 is 15.

Total number of stickers that Barbara used to decorate the diary
= 25 u + 21 u
= 46 u

46 u = 460

1 u = 460 ÷ 46 = 10

Number of black stickers that Barbara used to decorate the diary
= 6 u
= 6 x 10
= 60

Answer(s): 60