You found 20% of 750 instead of 40%. 100% - 60% = 40%, not 20%.
PRIMARY 5 · MATHEMATICS
Percentage
Top 5 mistakes
Ranked by how often they appear across 62 MOE-aligned practice questions in our archive.
You computed 750 - 500 by mistakenly using 500 as the girls (perhaps 2/3 of 750). 60% of 750 is 450, not 500.
450 is the number of GIRLS (60% of 750). The question asks for boys.
$90 is the discounted price BEFORE adding GST. You forgot the 9% GST.
You added 9% GST to $120 ($120 + $10.80) and got close to $130.80, but rounded. The discount must come first.
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