Peter saved some 20-cent coins and $1 notes in his coin box. The total value of the 20-cent coins to the total value of the $1 notes he had was in the ratio 1 : 3. After $24 worth of 20-cent coins and an equal value of $1 notes were added to the coin box, the ratio of the total value of 20-cent coins to the total value of $1 notes became 5 : 12. How many of each type did Peter have in the end?

1. 20-cent coins?
2. $1 notes?

	Value of 20-cent	Value of $1	Difference in  value
Before	1x7 = 7 u	3x7 = 21 u	2x7 = 14 u
Change	+ 24	+ 24
After	5x2 = 10 u	12x2 = 24 u	7x2 =  14 u

(a)
The difference in values between 20-cent and $1 remains unchanged. Make the difference in value the same. LCM of 2 and 7 is 14.

Increase in the value of 20-cent coins after more were added
= 10 u - 7 u
= 3 u

3 u = 24

1 u = 24 ÷ 3 = 8

Value of 20-cent coins in the end
= 10 u
= 10 x 8
= $80

100¢ = $1
20¢ = $0.20 

Number of 20-cent coins in the end
= 80 ÷ 0.20
= 400

(b)
Value of $1 notes in the end
= 24 u
= 24 x 8
= $192

Number of $1 notes in the end
= 192 ÷ 1
= 192

Answer(s): (a) 400; (b) 192