Bryan saved some 50-cent coins and $1 notes in his coin box. The total value of the 50-cent coins to the total value of the $1 notes he had was in the ratio 1 : 5. After $140 worth of 50-cent coins and an equal value of $1 notes were added to the coin box, the ratio of the total value of 50-cent coins to the total value of $1 notes became 9 : 10. How many of each type did Bryan have in the end?

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

	Value of 50-cent	Value of $1	Difference in  value
Before	1x1 = 1 u	5x1 = 5 u	4x1 = 4 u
Change	+ 140	+ 140
After	9x4 = 36 u	10x4 = 40 u	1x4 =  4 u

(a)
The difference in values between 50-cent and $1 remains unchanged. Make the difference in value the same. LCM of 4 and 1 is 4.

Increase in the value of 50-cent coins after more were added
= 36 u - 1 u
= 35 u

35 u = 140

1 u = 140 ÷ 35 = 4

Value of 50-cent coins in the end
= 36 u
= 36 x 4
= $144

100¢ = $1
50¢ = $0.50 

Number of 50-cent coins in the end
= 144 ÷ 0.50
= 288

(b)
Value of $1 notes in the end
= 40 u
= 40 x 4
= $160

Number of $1 notes in the end
= 160 ÷ 1
= 160

Answer(s): (a) 288; (b) 160