Problem 8 · 2012 Math Kangaroo
Easy
Algebra & Patterns
substitutionwork-backward
In the school for animals there are 3 cats, 2 ducks, 2 sheep and some dogs. The teacher counted the legs of all the animals and got 44. How many dogs go to the school?
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Answer: B — 5
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Hint 1 of 2
Count the legs you already know from the cats, ducks and sheep.
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Hint 2 of 2
Subtract those legs from 44, then see how many 4-legged dogs are left.
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Approach: account for known legs, then divide
- Cats: 3 x 4 = 12 legs. Sheep: 2 x 4 = 8 legs. Ducks: 2 x 2 = 4 legs.
- Known legs = 12 + 8 + 4 = 24.
- Dog legs = 44 - 24 = 20, and each dog has 4 legs, so 20 / 4 = 5 dogs.
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