PSLE
Liam had a collection of punchers, staplers and correction tapes. He had 13 punchers. 40% of his collection was staplers. He had 16 fewer staplers than correction tapes.

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

(a)
40% = ⁴⁰₁₀₀ = ²₅

Number of staplers = 2 u
Number of correction tapes = 2 u + 16
Number of punchers = 13
Total number of items = 5 u

5 u = 2 u + 2 u + 16 + 13
5 u - 4 u = 29
1 u = 29

Number of staplers
= 2 u
= 2 x 29
= 58

(b)
Total number of items at first
= 5 u
= 5 x 29
= 145

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

Number of items after giving away some staplers
= 80% x 145
= ⁸⁰₁₀₀ x 145
= 116

Number of correction tapes and punchers
= 5 u - 2 u
= 3 u
= 3 x 29
= 87

Number of staplers left
= 116 - 87
= 29

Percentage of his collection that was staplers after that
= ²⁹₁₁₆ x 100%
= 25%

Answer(s): (a) 58; (b) 25%