Problem 2 · 2020 Math Kangaroo
Easy
Arithmetic & Operations
divisionsum-constraint
Amira is travelling from Atown to Betown and passes two road signs (see picture). One number on a sign is hidden. What is this hidden number?
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Answer: C — 7
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Hint 1 of 2
The distance between the two towns is the same on both signs; add the two parts of the complete sign.
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Hint 2 of 2
Atown + Betown is fixed at 2+9=11, so the hidden Atown distance is 11 minus the known Betown distance.
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Approach: the total Atown-to-Betown distance is constant
- On the full sign, Atown is 2 km and Betown is 9 km, so the towns are 2+9 = 11 km apart.
- On the other sign Betown reads 4 km and the Atown number is hidden.
- Since the total must still be 11, the hidden number is 11 - 4 = 7.
Mark:
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