PSLE
Cole had a collection of markers, notebooks and glues. He had 86 markers. 30% of his collection was notebooks. He had 34 fewer notebooks than glues.

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

(a)
30% = ³⁰₁₀₀ = ³₁₀

Number of notebooks = 3 u
Number of glues = 3 u + 34
Number of markers = 86
Total number of items = 10 u

10 u = 3 u + 3 u + 34 + 86
10 u - 6 u = 120
4 u = 120

1 u = 120 ÷ 4 = 30

Number of notebooks
= 3 u
= 3 x 30
= 90

(b)
Total number of items at first
= 10 u
= 10 x 30
= 300

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

Number of items after giving away some notebooks
= 80% x 300
= ⁸⁰₁₀₀ x 300
= 240

Number of glues and markers
= 10 u - 3 u
= 7 u
= 7 x 30
= 210

Number of notebooks left
= 240 - 210
= 30

Percentage of his collection that was notebooks after that
= ³⁰₂₄₀ x 100%
= 12.5%

Answer(s): (a) 90; (b) 12.5%