PSLE
Gillian had a total of 206 blue and silver beads. She used 50 blue beads and 20% of the silver beads. After that, the ratio of the number of blue beads to silver beads Gillian had was 7 : 4.

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

	Blue beads	Silver beads	Total
Before	7 u + 50	5 u	12 u + 50
Change	- 50	- 1 u
After	7 u	4 u	11 u
Comparing blue beads and silver beads in the end	7	4	11

(a)
20% = ²⁰₁₀₀ = ¹₅

Fraction of her silver beads that Gillian used = ¹₅

(b)
The number of silver 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 silver beads at first = 5 u
Number of blue beads at first = 7 u + 50

Total number of beads at first
= 5 u + 7 u + 50
= 12 u + 50

12 u + 50 = 206
12 u = 206 - 50
12 u = 156

1 u = 156 ÷ 12 = 13

Number of silver beads in the end = 4 u
Number of blue beads in the end = 7 u

Total number of beads in the end
= 7 u + 4 u
= 11 u
= 11 x 13
= 143

Answer(s): (a)¹₅; (b) 143