PSLE
Sarah had a total of 251 silver and red beads. She used 41 silver beads and 30% of the red beads. After that, the ratio of the number of silver beads to red beads Sarah had was 5 : 7.

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

	Silver beads	Red beads	Total
Before	5 u + 41	10 u	15 u + 41
Change	- 41	- 3 u
After	5 u	7 u	12 u
Comparing silver beads and red beads in the end	5	7	12

(a)
30% = ³⁰₁₀₀ = ³₁₀

Fraction of her red beads that Sarah used = 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 silver beads at first = 5 u + 41

Total number of beads at first
= 10 u + 5 u + 41
= 15 u + 41

15 u + 41 = 251
15 u = 251 - 41
15 u = 210

1 u = 210 ÷ 15 = 14

Number of red beads in the end = 7 u
Number of silver beads in the end = 5 u

Total number of beads in the end
= 5 u + 7 u
= 12 u
= 12 x 14
= 168

Answer(s): (a)³₁₀; (b) 168