Betty used ⁴₇ of her black stickers and ³₇ of her green stickers to decorate her diary. In the end, she had an equal number of black stickers and green stickers left. Given that Betty had a total of 98 black and green stickers at first, how many green stickers did she use to decorate the diary?

	Black stickers	Green stickers
Before	7x4 = 28 u	7x3 = 21 u
Change	- 4x4 = - 16 u	- 3x3 = - 9 u
After	3x4 = 12 u	4x3 = 12 u

The number of black stickers and green stickers in the end is the same.  Make the number of black stickers and green stickers in the end the same.  LCM of 3 and 4 is 12.

Total number of stickers that Betty used to decorate the diary
= 28 u + 21 u
= 49 u

49 u = 98

1 u = 98 ÷ 49 = 2

Number of green stickers that Betty used to decorate the diary
= 9 u
= 9 x 2
= 18

Answer(s): 18