You computed the cost of beef as 2.5 x $14.20 = $35.50, but then subtracted $35.50 + $48.60 by mistake. The chicken cost is $50.40, not $48.60.
PRIMARY 5 · MATHEMATICS
Money
Top 5 mistakes
Ranked by how often they appear across 15 MOE-aligned practice questions in our archive.
You computed 100 - 6 x $8.40 - 2 x $14.20 = 100 - 50.40 - 28.40 = $21.20 (and miscopied). Re-check: beef weight is 2.5 kg, not 2 kg.
You found only the change after paying for chicken (100 - 50.40 = 49.60), forgetting to subtract the beef.
This comes from subtracting only one item: $25.00 − $12.50 = $12.50, then making an arithmetic slip, or subtracting $25.00 − $8.75 − $13.50 incorrectly. Both items must be added together first.
This comes from adding $12.50 + $9.00 = $21.50 and then $25.00 − $21.50 = $3.50. The cost of the notebook was $8.75, not $9.00.
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