Ravi baked 4 trays of muffins. Each tray had m muffins. He kept 5 muffins for himself and shared the rest equally among his 7 neighbours.
- How many muffins did each neighbour receive, in terms of m?
- Each neighbour received 9 muffins. Find the value of m.
Need a hint?
In (a), first find the total muffins in all 4 trays, then take away the 5 Ravi kept before dividing. In (b), work backwards from the 9 muffins each neighbour got.
Worked answer
- (a) 4 trays with m muffins each gives 4 × m = 4m muffins in all.
- (a) Ravi keeps 5, so 4m - 5 muffins are left to share.
- (a) Each neighbour gets (4m - 5) ÷ 7 muffins.
- (b) 9 muffins each to 7 neighbours is 9 × 7 = 63 muffins given out.
- (b) Add back the 5 he kept: 63 + 5 = 68 muffins in all.
- (b) Divide by 4 trays: 68 ÷ 4 = 17, so m = 17.
The mistake this question tests
Left out the units
Pupils often divide 4m by 7 first and then subtract 5, which gives 4m ÷ 7 - 5. The 5 muffins must be taken away from the total before sharing.
How to fix it at home →More PSLE algebra questions
A bakery had 15 small identical tins and 12 large identical tins
See the answer →Structured · 4mDaniel kept some $1 coins and some 20-cent coins in a tin
See the answer →Structured · 3mNora has s stickers
See the answer →Short answer · 2mAmir and Sofia are making a triangular sign for a community garden
See the answer →MCQ · 1mIn a video game, Ravi’s final score is represented by 16 + 7k + 9 – 2k + 11 – 6 points
See the answer →Structured · 3mA bag of marbles was shared among three children
See the answer →Practise PSLE algebra until the mistakes stop.
Three PSLE questions, free, no sign-up. You’ll see exactly where the marks went. Then 7 days of everything for S$4.99.