Wesley saved some 50-cent coins and $10 notes in his coin box. The total value of the 50-cent coins to the total value of the $10 notes he had was in the ratio 3 : 11. After $70 worth of 50-cent coins and an equal value of $10 notes were added to the coin box, the ratio of the total value of 50-cent coins to the total value of $10 notes became 5 : 9. How many of each type did Wesley have in the end?

1. 50-cent coins?
2. $10 notes?

	Value of 50-cent	Value of $10	Difference in  value
Before	3x1 = 3 u	11x1 = 11 u	8x1 = 8 u
Change	+ 70	+ 70
After	5x2 = 10 u	9x2 = 18 u	4x2 =  8 u

(a)
The difference in values between 50-cent and $10 remains unchanged. Make the difference in value the same. LCM of 8 and 4 is 8.

Increase in the value of 50-cent coins after more were added
= 10 u - 3 u
= 7 u

7 u = 70

1 u = 70 ÷ 7 = 10

Value of 50-cent coins in the end
= 10 u
= 10 x 10
= $100

100¢ = $1
50¢ = $0.50 

Number of 50-cent coins in the end
= 100 ÷ 0.50
= 200

(b)
Value of $10 notes in the end
= 18 u
= 18 x 10
= $180

Number of $10 notes in the end
= 180 ÷ 10
= 18

Answer(s): (a) 200; (b) 18