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2024 Math Kangaroo

Problem 12

Problem 12 · 2024 Math Kangaroo Medium
Arithmetic & Operations divisioncareful-counting

Penguin Peter goes fishing every day and brings home 9 fish for his two children. Each day he gives 5 fish to the first child he sees, and the other child gets the remaining 4 fish. Over the last few days, one child has received 26 fish in total. How many fish did the other child get?

Show answer
Answer: D — 28
Show hints
Hint 1 of 3
Every single day the two children together get 5 + 4 = 9 fish.
Still stuck? Show hint 2 →
Hint 2 of 3
Each day a child gets either 5 or 4, so try how many days it takes one child to reach 26.
Still stuck? Show hint 3 →
Hint 3 of 3
Once you know the number of days, the other child's total is 9 per day minus 26.
Show solution
Approach: find the number of days, then take the rest of the daily 9s
  1. Each day one child gets 5 fish and the other gets 4, so together they get 9 fish a day.
  2. For one child to reach 26 (made of 5s and 4s), it takes 6 days: 5 + 5 + 4 + 4 + 4 + 4 = 26.
  3. In all, the children got 9 × 6 = 54 fish over those 6 days.
  4. So the other child got 54 − 26 = 28 (D).
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