Problem 1 · 2010 Math Kangaroo
Easy
Algebra & Patterns
substitution
Given that ▲ + ▲ + 6 = ▲ + ▲ + ▲ + ▲, which number should replace ▲?
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Answer: B — 3
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Hint 1 of 2
Both sides of the balance have some triangles in common.
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Hint 2 of 2
Cover up the two triangles that show up on both sides and see what is left.
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Approach: match the equal parts on both sides
- The left side has 2 triangles, the right side has 4 triangles, so 2 of them appear on both sides.
- Cover those matching 2 triangles on each side; what is left is \(6 = \) two triangles.
- Two triangles make 6, so one triangle is \(6 \div 2 = 3\) — the answer is B.
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