Simon had 40 coins. ³₄ were blue and the rest were yellow and silver. The ratio of the number of yellow coins to the number of silver coins was 1 : 4. Simon decided to give away some blue coins to decrease the number of blue coins to half of the total number of coins.

1. How many more blue coins than yellow coins did he have at first?
2. How many blue coins did he have to give away?

Blue coins	Yellow coins	Silver coins	Total
3x5	1x5
	1x1	4x1
15 u	1 u	4 u	40

	Blue coins	Yellow coins	Silver coins
Before	15 u	1 u	4 u
Change	- ?
After	5 u	5 u
Comparing blue, yellow and silver coins in the end	1	1

(a)
The total number of yellow coins and silver coins is repeated. Make the total number of yellow coins and silver coins the same.  LCM of 1 and 5 is 5.

Total number of coins at first
= 15 u + 1 u + 4 u
= 20 u

20 u = 40

1 u = 40 ÷ 20 = 2

Number of more blue coins than yellow coins at first
= 15 u - 1 u
= 14 u
= 14 x 2
= 28

(b)
Number of more blue coins that Simon had to give away
= 15 u - 5 u
= 10 u
= 10 x 2
= 20

Answer(s): (a) 28; (b) 20