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2016 Math Kangaroo

Problem 20

Problem 20 · 2016 Math Kangaroo Stretch
Arithmetic & Operations sum-constraint

Lisa's dogs have 18 more legs than noses. How many dogs does Lisa have?

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Answer: C — 6
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Hint 1 of 2
Each dog has 4 legs but only 1 nose, so each dog adds 3 extra legs over noses.
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Hint 2 of 2
Divide the 18 extra legs by 3 per dog.
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Approach: count the leg-minus-nose difference per dog
  1. Every dog has 4 legs and 1 nose, so it contributes 4 − 1 = 3 more legs than noses.
  2. All dogs together give 18 extra legs, so there are 18 ÷ 3 = 6 dogs.
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