PSLE
Liam had a collection of post-it pads, foolscaps and correction tapes. He had 13 post-it pads. 40% of his collection was foolscaps. He had 11 fewer foolscaps than correction tapes.

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

(a)
40% = ⁴⁰₁₀₀ = ²₅

Number of foolscaps = 2 u
Number of correction tapes = 2 u + 11
Number of post-it pads = 13
Total number of items = 5 u

5 u = 2 u + 2 u + 11 + 13
5 u - 4 u = 24
1 u = 24

Number of foolscaps
= 2 u
= 2 x 24
= 48

(b)
Total number of items at first
= 5 u
= 5 x 24
= 120

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

Number of items after giving away some foolscaps
= 80% x 120
= ⁸⁰₁₀₀ x 120
= 96

Number of correction tapes and post-it pads
= 5 u - 2 u
= 3 u
= 3 x 24
= 72

Number of foolscaps left
= 96 - 72
= 24

Percentage of his collection that was foolscaps after that
= ²⁴₉₆ x 100%
= 25%

Answer(s): (a) 48; (b) 25%