PSLE
Tom had a collection of files, foolscaps and correction tapes. He had 99 files. 15% of his collection was foolscaps. He had 41 fewer foolscaps than correction tapes.

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

(a)
15% = ¹⁵₁₀₀ = ³₂₀

Number of foolscaps = 3 u
Number of correction tapes = 3 u + 41
Number of files = 99
Total number of items = 20 u

20 u = 3 u + 3 u + 41 + 99
20 u - 6 u = 140
14 u = 140

1 u = 140 ÷ 14 = 10

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

(b)
Total number of items at first
= 20 u
= 20 x 10
= 200

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

Number of items after giving away some foolscaps
= 80% x 200
= ⁸⁰₁₀₀ x 200
= 160

Number of correction tapes and files
= 20 u - 3 u
= 17 u
= 17 x 10
= 170

Number of foolscaps left
= 160 - 170
= 10

Percentage of his collection that was foolscaps after that
= ¹⁰₁₆₀ x 100%
= 6.25%

Answer(s): (a) 30; (b) 6.25%