PSLE
Sabrina had a total of 238 red and black beads. She used 43 red beads and 90% of the black beads. After that, the ratio of the number of red beads to black beads Sabrina had was 5 : 1.

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

	Red	Black	Total
Before	5 u + 43	10 u	15 u + 43
Change	- 43	- 9 u
After	5 u	1 u	6 u
Comparing red beads and black beads in the end	5	1	6

(a)
90% = ⁹⁰₁₀₀ = ⁹₁₀

Fraction of her black beads that Sabrina used = ⁹₁₀

Fraction of her black beads that Sabrina was left with
= 1 - ⁹₁₀
= ¹₁₀

(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 = 10 u
Number of red beads at first = 5 u + 43

Total number of beads at first
= 10 u + 5 u + 43
= 15 u + 43

15 u + 43 = 238
15 u = 238 - 43
15 u = 195

1 u = 195 ÷ 15 = 13

Number of black beads in the end = 1 u
Number of red beads in the end = 5 u

Number of more red beads than black beads that Sabrina had in the end
= 5 u - 1 u
= 4 u
= 4 x 13
= 52

Answer(s): (a)¹₁₀; (b) 52