PSLE
Cindy had a total of 93 black and yellow beads. She used 13 black beads and 20% of the yellow beads. After that, the ratio of the number of black beads to yellow beads Cindy had was 5 : 4.

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

	Black beads	Yellow beads	Total
Before	5 u + 13	5 u	10 u + 13
Change	- 13	- 1 u
After	5 u	4 u	9 u
Comparing black beads and yellow beads in the end	5	4	9

(a)
20% = ²⁰₁₀₀ = ¹₅

Fraction of her yellow beads that Cindy used = ¹₅

(b)
The number of yellow 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 yellow beads at first = 5 u
Number of black beads at first = 5 u + 13

Total number of beads at first
= 5 u + 5 u + 13
= 10 u + 13

10 u + 13 = 93
10 u = 93 - 13
10 u = 80

1 u = 80 ÷ 10 = 8

Number of yellow beads in the end = 4 u
Number of black beads in the end = 5 u

Total number of beads in the end
= 5 u + 4 u
= 9 u
= 9 x 8
= 72

Answer(s): (a)¹₅; (b) 72