PSLE
Yen had a total of 187 blue and red beads. She used 19 blue beads and 25% of the red beads. After that, the ratio of the number of blue beads to red beads Yen had was 10 : 3.

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

	Blue beads	Red beads	Total
Before	10 u + 19	4 u	14 u + 19
Change	- 19	- 1 u
After	10 u	3 u	13 u
Comparing blue beads and red beads in the end	10	3	13

(a)
25% = ²⁵₁₀₀ = ¹₄

Fraction of her red beads that Yen used = ¹₄

(b)
The number of red 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 red beads at first = 4 u
Number of blue beads at first = 10 u + 19

Total number of beads at first
= 4 u + 10 u + 19
= 14 u + 19

14 u + 19 = 187
14 u = 187 - 19
14 u = 168

1 u = 168 ÷ 14 = 12

Number of red beads in the end = 3 u
Number of blue beads in the end = 10 u

Total number of beads in the end
= 10 u + 3 u
= 13 u
= 13 x 12
= 156

Answer(s): (a)¹₄; (b) 156