Problem 6 · 2010 Math Kangaroo
Easy
Arithmetic & Operations
total-then-divide
A fly has 6 legs and a spider has 8 legs. Together, 2 flies and 3 spiders have as many legs as 10 birds and …
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Answer: C — 4 cats
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Hint 1 of 2
Add up all the legs on the left side: the flies and the spiders together.
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Hint 2 of 2
Take away the legs of the 10 birds, then share what is left into groups of 4 (a cat's legs).
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Approach: count legs on each side
- The flies and spiders have \(2 \times 6 + 3 \times 8 = 12 + 24 = 36\) legs.
- The 10 birds have \(10 \times 2 = 20\) legs, so \(36 - 20 = 16\) legs are still needed.
- Cats have 4 legs each, and \(16 \div 4 = 4\), so it is 4 cats (answer C).
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