Unsimplified.
PRIMARY 6 · MATHEMATICS
Ratio
Top 5 mistakes
Ranked by how often they appear across 161 MOE-aligned practice questions in our archive.
Reversed order.
Took $24 divided by (5 - 3) = 2 to get 1 unit = $12, but then multiplied by 3 (new watch units) instead of 5 (original watch units): 3 x $12 = $36.
Used $24 divided by 3 (the new watch units) = $8 per unit, then multiplied by 5 original watch units: 5 x $8 = $40.
Added the $24 discount to the original watch instead of subtracting; assumed new watch = 5u + $24 = 3u, giving u = -$12 then took absolute value: 6 x $12 = $72.
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