Kathy had 126 stickers. ³₇ were yellow and the rest were brown and green. The ratio of the number of brown stickers to the number of green stickers was 1 : 2. Kathy decided to buy some more yellow stickers to increase the number of yellow stickers to half of the total number of stickers.

1. How many less brown stickers than yellow stickers did he have at first?
2. How many more yellow stickers did he have to buy?

Yellow stickers	Brown stickers	Green stickers	Total
3x3	4x3
	1x4	2x4
9 u	4 u	8 u	126

	Yellow stickers	Brown stickers	Green stickers
Before	9 u	4 u	8 u
Change	+ ?
After	12 u	12 u
Comparing yellow, brown and green stickers in the end	1	1

(a)
The total number of brown stickers and green stickers is repeated. Make the total number of brown stickers and green stickers the same.  LCM of 4 and 3 is 12.

Total number of stickers at first
= 9 u + 4 u + 8 u
= 21 u

21 u = 126

1 u = 126 ÷ 21 = 6

Number of less brown stickers than yellow stickers at first
= 9 u - 4 u
= 5 u
= 5 x 6
= 30

(b)
Number of more yellow stickers that Kathy had to buy
= 12 u - 9 u
= 3 u
= 3 x 6
= 18

Answer(s): (a) 30; (b) 18