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2012 Math Kangaroo

Problem 10

Problem 10 · 2012 Math Kangaroo Medium
Algebra & Patterns substitution

3 balloons cost 12 cents more than 1 balloon. How much does 1 balloon cost?

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Answer: B — 6 cents
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Hint 1 of 2
Three balloons cost the same as one balloon plus 12 cents, so what do the two extra balloons cost?
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Hint 2 of 2
Two balloons cost 12 cents; halve that for one balloon.
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Approach: compare three balloons with one balloon
  1. 3 balloons cost 12 cents more than 1 balloon, so the extra 2 balloons cost 12 cents.
  2. Then 1 balloon costs 12 / 2 = 6 cents.
  3. So one balloon costs 6 cents.
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