PSLE
Barbara had a total of 290 blue and red beads. She used 18 blue beads and 70% of the red beads. After that, the ratio of the number of blue beads to red beads Barbara had was 7 : 3.

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

	Blue	Red	Total
Before	7 u + 18	10 u	17 u + 18
Change	- 18	- 7 u
After	7 u	3 u	10 u
Comparing blue beads and red beads in the end	7	3	10

(a)
70% = ⁷⁰₁₀₀ = ⁷₁₀

Fraction of her red beads that Barbara used = ⁷₁₀

Fraction of her red beads that Barbara was left with
= 1 - ⁷₁₀
= ³₁₀

(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 blue beads at first = 7 u + 18

Total number of beads at first
= 10 u + 7 u + 18
= 17 u + 18

17 u + 18 = 290
17 u = 290 - 18
17 u = 272

1 u = 272 ÷ 17 = 16

Number of red beads in the end = 3 u
Number of blue beads in the end = 7 u

Number of more blue beads than red beads that Barbara had in the end
= 7 u - 3 u
= 4 u
= 4 x 16
= 64

Answer(s): (a)³₁₀; (b) 64