Problem 9 · 2010 Math Kangaroo
Medium
Arithmetic & Operations
matching
Suppose ▲ + ▲ + 6 = ▲ + ▲ + ▲ + ▲. Which number should replace ▲?
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Answer: B — 3
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Hint 1 of 2
Both sides have two triangles, so cover those up with your finger on each side.
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Hint 2 of 2
Whatever is left over on the two sides must still be equal.
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Approach: match the same triangles on both sides and see what is left
- The left side is two triangles and a 6; the right side is two triangles and two more triangles.
- Cover the two matching triangles on each side, and the 6 is left on the left while two triangles are left on the right.
- So two triangles make 6, which means one triangle is 6 split into 2 equal parts, or 3.
- The triangle is 3, choice B.
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