PSLE
Betty had a total of 111 green and blue beads. She used 12 green beads and 10% of the blue beads. After that, the ratio of the number of green beads to blue beads Betty had was 1 : 9.

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

	Green beads	Blue beads	Total
Before	1 u + 12	10 u	11 u + 12
Change	- 12	- 1 u
After	1 u	9 u	10 u
Comparing green beads and blue beads in the end	1	9	10

(a)
10% = ¹⁰₁₀₀ = ¹₁₀

Fraction of her blue beads that Betty used = ¹₁₀

(b)
The number of blue 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 blue beads at first = 10 u
Number of green beads at first = 1 u + 12

Total number of beads at first
= 10 u + 1 u + 12
= 11 u + 12

11 u + 12 = 111
11 u = 111 - 12
11 u = 99

1 u = 99 ÷ 11 = 9

Number of blue beads in the end = 9 u
Number of green beads in the end = 1 u

Total number of beads in the end
= 1 u + 9 u
= 10 u
= 10 x 9
= 90

Answer(s): (a)¹₁₀; (b) 90