Ivan had 42 erasers. ⁵₇ were pink and the rest were green and white. The ratio of the number of green erasers to the number of white erasers was 1 : 5. Ivan decided to give away some pink erasers to decrease the number of pink erasers to half of the total number of erasers.

1. How many more pink erasers than green erasers did he have at first?
2. How many pink erasers did he have to give away?

Pink erasers	Green erasers	White erasers	Total
5x3	2x3
	1x1	5x1
15 u	1 u	5 u	42

	Pink erasers	Green erasers	White erasers
Before	15 u	1 u	5 u
Change	- ?
After	6 u	6 u
Comparing pink, green and white erasers in the end	1	1

(a)
The total number of green erasers and white erasers is repeated. Make the total number of green erasers and white erasers the same.  LCM of 2 and 6 is 6.

Total number of erasers at first
= 15 u + 1 u + 5 u
= 21 u

21 u = 42

1 u = 42 ÷ 21 = 2

Number of more pink erasers than green erasers at first
= 15 u - 1 u
= 14 u
= 14 x 2
= 28

(b)
Number of more pink erasers that Ivan had to give away
= 15 u - 6 u
= 9 u
= 9 x 2
= 18

Answer(s): (a) 28; (b) 18