PSLE
Diana had a total of 78 blue and pink beads. She used 18 blue beads and 40% of the pink beads. After that, the ratio of the number of blue beads to pink beads Diana had was 7 : 3.

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

	Blue beads	Pink beads	Total
Before	7 u + 18	5 u	12 u + 18
Change	- 18	- 2 u
After	7 u	3 u	10 u
Comparing blue beads and pink beads in the end	7	3	10

(a)
40% = ⁴⁰₁₀₀ = ²₅

Fraction of her pink beads that Diana used = ²₅

(b)
The number of pink 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 pink beads at first = 5 u
Number of blue beads at first = 7 u + 18

Total number of beads at first
= 5 u + 7 u + 18
= 12 u + 18

12 u + 18 = 78
12 u = 78 - 18
12 u = 60

1 u = 60 ÷ 12 = 5

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

Total number of beads in the end
= 7 u + 3 u
= 10 u
= 10 x 5
= 50

Answer(s): (a)²₅; (b) 50