PSLE
Emily had a total of 235 yellow and black beads. She used 15 yellow beads and 50% of the black beads. After that, the ratio of the number of yellow beads to black beads Emily had was 9 : 1.

1. What fraction of her black beads was Emily left with? Give your answer in the simplest form.
2. How many more yellow beads than black beads did Emily have in the end?

	Yellow	Black	Total
Before	9 u + 15	2 u	11 u + 15
Change	- 15	- 1 u
After	9 u	1 u	10 u
Comparing yellow beads and black beads in the end	9	1	10

(a)
50% = ⁵⁰₁₀₀ = ¹₂

Fraction of her black beads that Emily used = ¹₂

Fraction of her black beads that Emily was left with
= 1 - ¹₂
= ¹₂

(b)
The number of black 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 black beads at first = 2 u
Number of yellow beads at first = 9 u + 15

Total number of beads at first
= 2 u + 9 u + 15
= 11 u + 15

11 u + 15 = 235
11 u = 235 - 15
11 u = 220

1 u = 220 ÷ 11 = 20

Number of black beads in the end = 1 u
Number of yellow beads in the end = 9 u

Number of more yellow beads than black beads that Emily had in the end
= 9 u - 1 u
= 8 u
= 8 x 20
= 160

Answer(s): (a)¹₂; (b) 160