PSLE
Xuan had a total of 96 black and green beads. She used 21 black beads and 10% of the green beads. After that, the ratio of the number of black beads to green beads Xuan had was 5 : 9.

1. What fraction of her green beads did Xuan use? Give your answer in the simplest form.
2. How many beads did Xuan have in the end?

	Black beads	Green beads	Total
Before	5 u + 21	10 u	15 u + 21
Change	- 21	- 1 u
After	5 u	9 u	14 u
Comparing black beads and green beads in the end	5	9	14

(a)
10% = ¹⁰₁₀₀ = ¹₁₀

Fraction of her green beads that Xuan used = ¹₁₀

(b)
The number of green beads in the end is repeated.
Since the numbers are already the same, we do not need to use LCM to make them the same.

Number of green beads at first = 10 u
Number of black beads at first = 5 u + 21

Total number of beads at first
= 10 u + 5 u + 21
= 15 u + 21

15 u + 21 = 96
15 u = 96 - 21
15 u = 75

1 u = 75 ÷ 15 = 5

Number of green beads in the end = 9 u
Number of black beads in the end = 5 u

Total number of beads in the end
= 5 u + 9 u
= 14 u
= 14 x 5
= 70

Answer(s): (a)¹₁₀; (b) 70