PSLE
George had a collection of pencils, highlighters and punchers. He had 183 pencils. 15% of his collection was highlighters. He had 27 fewer highlighters than punchers.

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

(a)
15% = ¹⁵₁₀₀ = ³₂₀

Number of highlighters = 3 u
Number of punchers = 3 u + 27
Number of pencils = 183
Total number of items = 20 u

20 u = 3 u + 3 u + 27 + 183
20 u - 6 u = 210
14 u = 210

1 u = 210 ÷ 14 = 15

Number of highlighters
= 3 u
= 3 x 15
= 45

(b)
Total number of items at first
= 20 u
= 20 x 15
= 300

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

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

Number of punchers and pencils
= 20 u - 3 u
= 17 u
= 17 x 15
= 255

Number of highlighters left
= 240 - 255
= 15

Percentage of his collection that was highlighters after that
= ¹⁵₂₄₀ x 100%
= 6.25%

Answer(s): (a) 45; (b) 6.25%