Problem 3 · 2010 Math Kangaroo
Easy
Arithmetic & Operations
total-then-divide
A fly has 6 legs and a spider has 8. 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
First count all the legs on the left side of the comparison.
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Hint 2 of 2
Subtract the birds' legs, then see how many 4-legged animals fill the gap.
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Approach: count legs, then divide the leftover
- 2 flies = 2×6 = 12 legs; 3 spiders = 3×8 = 24 legs; together 36 legs.
- 10 birds have 10×2 = 20 legs.
- The remaining 36−20 = 16 legs come from cats: 16÷4 = 4 cats.
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