PSLE
Gem had a total of 211 black and blue beads. She used 15 black beads and 80% of the blue beads. After that, the ratio of the number of black beads to blue beads Gem had was 9 : 1.

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

	Black beads	Blue beads	Total
Before	9 u + 15	5 u	14 u + 15
Change	- 15	- 4 u
After	9 u	1 u	10 u
Comparing black beads and blue beads in the end	9	1	10

(a)
80% = ⁸⁰₁₀₀ = ⁴₅

Fraction of her blue beads that Gem used = ⁴₅

(b)
The number of blue 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 blue beads at first = 5 u
Number of black beads at first = 9 u + 15

Total number of beads at first
= 5 u + 9 u + 15
= 14 u + 15

14 u + 15 = 211
14 u = 211 - 15
14 u = 196

1 u = 196 ÷ 14 = 14

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

Total number of beads in the end
= 9 u + 1 u
= 10 u
= 10 x 14
= 140

Answer(s): (a)⁴₅; (b) 140