Tommy had 140 pens. ⁵₇ were green and the rest were silver and pink. The ratio of the number of silver pens to the number of pink pens was 1 : 4. Tommy decided to give away some green pens to decrease the number of green pens to half of the total number of pens.

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

Green pens	Silver pens	Pink pens	Total
5x5	2x5
	1x2	4x2
25 u	2 u	8 u	140

	Green pens	Silver pens	Pink pens
Before	25 u	2 u	8 u
Change	- ?
After	10 u	10 u
Comparing green, silver and pink pens in the end	1	1

(a)
The total number of silver pens and pink pens is repeated. Make the total number of silver pens and pink pens the same.  LCM of 2 and 5 is 10.

Total number of pens at first
= 25 u + 2 u + 8 u
= 35 u

35 u = 140

1 u = 140 ÷ 35 = 4

Number of more green pens than silver pens at first
= 25 u - 2 u
= 23 u
= 23 x 4
= 92

(b)
Number of more green pens that Tommy had to give away
= 25 u - 10 u
= 15 u
= 15 x 4
= 60

Answer(s): (a) 92; (b) 60