$\"\"$

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The arithmetic sequence is $\"\"$ .

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The nth term of an arithmetic sequence is $\"\"$ .

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Here $\"\"$ is first term of the sequence and d is common difference.

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$\"\"$

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ ) $\"\"$

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Apply subtraction property of equality: a = b then $\"\"$ .

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$\"\"$ (Subtract 10 from each side)

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Apply commutative property of addition: $\"\"$ .

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$\"\"$

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$\"\"$ (Apply additive inverse property: $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ ) $\"\"$

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Apply division property of equality: a = b then $\"\"$ .

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$\"\"$ (Divide each side by 3)

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$\"\"$ (Cancel common term)

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$\"\"$ (Divide: $\"\"$ ) $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ $\"\"$

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The arithmetic means are $\"\"$ .