Example 1 — Marbles
EasyProblem
Maya has 3 more than twice as many marbles as Sam, and together they have 18. How many does Sam have?
Solution
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A worded scenario with an unknown, so define a variable and model it.
Name the structure before touching arithmetic — that is what makes the right method obvious.
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Ask the recognition question: Must I translate a worded scenario into an equation or expression before I can compute?
If the answer is yes, the concept applies; the cue, not a keyword, decides the method.
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Let = Sam's marbles; Maya ; equation .
The rule is chosen only after the structure matches, so the steps mean something.
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Keep units, shape, or answer form tied to the story so the work does not become symbol pushing.
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Check the answer against the original question.
It should fit the mental model — translate the story into a structure first. If it does not, revisit the recognition step before changing the arithmetic.
Answer
Sam has 5 marbles
Takeaway: Translate the story into an equation before choosing a procedure.