Kylie had some yellow pens and silver pens in 2 boxes. In Box G, the ratio of the number of yellow pens to silver pens was 9 : 4. In Box H, the number of yellow pens was 2 times the number of silver pens. Kylie transferred ³₄ of the silver pens from Box G to Box H. The number of pens in Box G became 120 and the ratio of the number of yellow pens to silver pens in Box H became 6 : 7.

1. How many silver pens were transferred from Box G to Box H?
2. What was the number of pens in Box H after the transfer?

	Box G		Box H
	Yellow	Silver	Yellow	Silver
Comparing yellow pens and silver pens at first	9 u	4 u	2x3 = 6 p	1x3 = 3 p
Before		4 u
Change		- 3 u		+ 3 u
After		1 u
Comparing yellow pens and silver pens in the end	9 u	1 u	6 p	7 p

(a)
Total number of pens in the end for Box G
= 9 u + 1 u
= 10 u

10 u = 120

1 u = 120 ÷ 10 = 12

Number of silver pens that were transferred from Box G to Box H
= 3 u
= 3 x 12
= 36

(b)
The number of yellow pens in Box H remains unchanged.  Make the number of yellow pens in Box H the same.  LCM of 2 and 6 is 6. 

Increase in the number of silver pens in Box H
= 7 p - 3 p
= 4 p

4 p = 3 u
4 p = 36

1 p = 36 ÷ 4 = 9

Number of pens in Box H in the end
= 6 p + 7 p
= 13 p
= 13 x 9
= 117

Answer(s): (a) 36; (b) 117