Jean had some grey stickers and gold stickers in 2 boxes. In Box R, the ratio of the number of grey stickers to gold stickers was 9 : 7. In Box S, the number of grey stickers was 2 times the number of gold stickers. Jean transferred ⁴₇ of the gold stickers from Box R to Box S. The number of stickers in Box R became 72 and the ratio of the number of grey stickers to gold stickers in Box S became 4 : 5.

1. How many gold stickers were transferred from Box R to Box S?
2. What was the number of stickers in Box S after the transfer?

	Box R		Box S
	Grey	Gold	Grey	Gold
Comparing grey stickers and gold stickers at first	9 u	7 u	2x2 = 4 p	1x2 = 2 p
Before		7 u
Change		- 4 u		+ 4 u
After		3 u
Comparing grey stickers and gold stickers in the end	9 u	3 u	4 p	5 p

(a)
Total number of stickers in the end for Box R
= 9 u + 3 u
= 12 u

12 u = 72

1 u = 72 ÷ 12 = 6

Number of gold stickers that were transferred from Box R to Box S
= 4 u
= 4 x 6
= 24

(b)
The number of grey stickers in Box S remains unchanged.  Make the number of grey stickers in Box S the same.  LCM of 2 and 4 is 4. 

Increase in the number of gold stickers in Box S
= 5 p - 2 p
= 3 p

3 p = 4 u
3 p = 24

1 p = 24 ÷ 3 = 8

Number of stickers in Box S in the end
= 4 p + 5 p
= 9 p
= 9 x 8
= 72

Answer(s): (a) 24; (b) 72