Eric 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 : 2. After $18 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 5 : 8. How many of each type did Eric have in the end?

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

	Value of 20-cent	Value of $2	Difference in  value
Before	1x3 = 3 u	2x3 = 6 u	1x3 = 3 u
Change	+ 18	+ 18
After	5x1 = 5 u	8x1 = 8 u	3x1 =  3 u

(a)
The difference in values between 20-cent and $2 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
= 5 u - 3 u
= 2 u

2 u = 18

1 u = 18 ÷ 2 = 9

Value of 20-cent coins in the end
= 5 u
= 5 x 9
= $45

100¢ = $1
20¢ = $0.20 

Number of 20-cent coins in the end
= 45 ÷ 0.20
= 225

(b)
Value of $2 notes in the end
= 8 u
= 8 x 9
= $72

Number of $2 notes in the end
= 72 ÷ 2
= 36

Answer(s): (a) 225; (b) 36