Jen had some pink erasers and silver erasers in 2 bags. In Bag C, the ratio of the number of pink erasers to silver erasers was 10 : 7. In Bag D, the number of pink erasers was 2 times the number of silver erasers. Jen transferred ³₇ of the silver erasers from Bag C to Bag D. The number of erasers in Bag C became 56 and the ratio of the number of pink erasers to silver erasers in Bag D became 6 : 7.

1. How many silver erasers were transferred from Bag C to Bag D?
2. What was the number of erasers in Bag D after the transfer?

	Bag C		Bag D
	Pink	Silver	Pink	Silver
Comparing pink erasers and silver erasers at first	10 u	7 u	2x3 = 6 p	1x3 = 3 p
Before		7 u
Change		- 3 u		+ 3 u
After		4 u
Comparing pink erasers and silver erasers in the end	10 u	4 u	6 p	7 p

(a)
Total number of erasers in the end for Bag C
= 10 u + 4 u
= 14 u

14 u = 56

1 u = 56 ÷ 14 = 4

Number of silver erasers that were transferred from Bag C to Bag D
= 3 u
= 3 x 4
= 12

(b)
The number of pink erasers in Bag D remains unchanged.  Make the number of pink erasers in Bag D the same.  LCM of 2 and 6 is 6. 

Increase in the number of silver erasers in Bag D
= 7 p - 3 p
= 4 p

4 p = 3 u
4 p = 12

1 p = 12 ÷ 4 = 3

Number of erasers in Bag D in the end
= 6 p + 7 p
= 13 p
= 13 x 3
= 39

Answer(s): (a) 12; (b) 39