Jenson saved some 20-cent coins and $2 notes in his coin box. The total value of the 20-cent coins to the total value of the $2 notes he had was in the ratio 1 : 3. After $21 worth of 20-cent coins and an equal value of $2 notes were added to the coin box, the ratio of the total value of 20-cent coins to the total value of $2 notes became 2 : 3. How many of each type did Jenson have in the end?

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

	Value of 20-cent	Value of $2	Difference in  value
Before	1x1 = 1 u	3x1 = 3 u	2x1 = 2 u
Change	+ 21	+ 21
After	2x2 = 4 u	3x2 = 6 u	1x2 =  2 u

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

Increase in the value of 20-cent coins after more were added
= 4 u - 1 u
= 3 u

3 u = 21

1 u = 21 ÷ 3 = 7

Value of 20-cent coins in the end
= 4 u
= 4 x 7
= $28

100¢ = $1
20¢ = $0.20 

Number of 20-cent coins in the end
= 28 ÷ 0.20
= 140

(b)
Value of $2 notes in the end
= 6 u
= 6 x 7
= $42

Number of $2 notes in the end
= 42 ÷ 2
= 21

Answer(s): (a) 140; (b) 21