PSLE
Xandra had a total of 133 green and red beads. She used 16 green beads and 90% of the red beads. After that, the ratio of the number of green beads to red beads Xandra had was 3 : 1.

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

	Green beads	Red beads	Total
Before	3 u + 16	10 u	13 u + 16
Change	- 16	- 9 u
After	3 u	1 u	4 u
Comparing green beads and red beads in the end	3	1	4

(a)
90% = ⁹⁰₁₀₀ = ⁹₁₀

Fraction of her red beads that Xandra used = ⁹₁₀

(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 = 10 u
Number of green beads at first = 3 u + 16

Total number of beads at first
= 10 u + 3 u + 16
= 13 u + 16

13 u + 16 = 133
13 u = 133 - 16
13 u = 117

1 u = 117 ÷ 13 = 9

Number of red beads in the end = 1 u
Number of green beads in the end = 3 u

Total number of beads in the end
= 3 u + 1 u
= 4 u
= 4 x 9
= 36

Answer(s): (a)⁹₁₀; (b) 36