Henry saved some 20-cent coins and $10 notes in his coin box. The total value of the 20-cent coins to the total value of the $10 notes he had was in the ratio 1 : 2. After $32 worth of 20-cent coins and an equal value of $10 notes were added to the coin box, the ratio of the total value of 20-cent coins to the total value of $10 notes became 7 : 10. How many of each type did Henry have in the end?

1. 20-cent coins?
2. $10 notes?

	Value of 20-cent	Value of $10	Difference in  value
Before	1x3 = 3 u	2x3 = 6 u	1x3 = 3 u
Change	+ 32	+ 32
After	7x1 = 7 u	10x1 = 10 u	3x1 =  3 u

(a)
The difference in values between 20-cent and $10 remains unchanged. Make the difference in value the same. LCM of 1 and 3 is 3.

Increase in the value of 20-cent coins after more were added
= 7 u - 3 u
= 4 u

4 u = 32

1 u = 32 ÷ 4 = 8

Value of 20-cent coins in the end
= 7 u
= 7 x 8
= $56

100¢ = $1
20¢ = $0.20 

Number of 20-cent coins in the end
= 56 ÷ 0.20
= 280

(b)
Value of $10 notes in the end
= 10 u
= 10 x 8
= $80

Number of $10 notes in the end
= 80 ÷ 10
= 8

Answer(s): (a) 280; (b) 8