Nora used ⁵₇ 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 Nora had a total of 294 white and black stickers at first, how many black stickers did she use to decorate the diary?

	White stickers	Black stickers
Before	7x5 = 35 u	7x2 = 14 u
Change	- 5x5 = - 25 u	- 2x2 = - 4 u
After	2x5 = 10 u	5x2 = 10 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 2 and 5 is 10.

Total number of stickers that Nora used to decorate the diary
= 35 u + 14 u
= 49 u

49 u = 294

1 u = 294 ÷ 49 = 6

Number of black stickers that Nora used to decorate the diary
= 4 u
= 4 x 6
= 24

Answer(s): 24