$\"\"$

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The equation is, $\"\"$ .

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According to addition property of equality: If a = b then a + c = b + c.

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$\"\"$ (Add 1.2 to each sides).

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$\"\"$ (Additive inverse property: $\"\"$ ) \ \

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$\"\"$ (Add: 0.9 + 1.2 = 2.1) \ \

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$\"\"$

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According to division property of equality:

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For any number a, b and c, If a = b then $\"\"$ .

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$\"\"$ (Divide each sides by - 3)

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$\"\"$ (Cancel common terms)

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

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$\"\"$

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Check:

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To check the solution, substitute $\"\"$ in original equation.

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$\"\"$

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$\"\"$ (Multiply: $\"\"$ ) \ \

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

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Compare the values, the equation is true.

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$\"\"$

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The value of $\"\"$ .