PSLE
Cody had a collection of folders, staplers and punchers. He had 27 folders. 30% of his collection was staplers. He had 13 fewer staplers than punchers.

1. How many staplers did Cody have?
2. Cody gave away some staplers. His total collection decreased by 20%. What percentage of his collection was staplers after that?

(a)
30% = ³⁰₁₀₀ = ³₁₀

Number of staplers = 3 u
Number of punchers = 3 u + 13
Number of folders = 27
Total number of items = 10 u

10 u = 3 u + 3 u + 13 + 27
10 u - 6 u = 40
4 u = 40

1 u = 40 ÷ 4 = 10

Number of staplers
= 3 u
= 3 x 10
= 30

(b)
Total number of items at first
= 10 u
= 10 x 10
= 100

Total collection in the end in percent
= 100% - 20%
= 80%

Number of items after giving away some staplers
= 80% x 100
= ⁸⁰₁₀₀ x 100
= 80

Number of punchers and folders
= 10 u - 3 u
= 7 u
= 7 x 10
= 70

Number of staplers left
= 80 - 70
= 10

Percentage of his collection that was staplers after that
= ¹⁰₈₀ x 100%
= 12.5%

Answer(s): (a) 30; (b) 12.5%