\"\"

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The given equation is \"\"

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\"\"     (Using distributive property: a (b+c) =ab+ac)

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\"\"              (Multiply: 12(3) =36; 2(5) =10)

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\"\"              (Using commutative property: a+b=b+a)

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

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\"\"          (Add r to each side)

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\"\"          (Using commutative property: a+b=b+a)

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\"\"                             (Add:\"\")

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\"\"             (Subtract 36 from each side)

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

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\"\"                              (Divide each side by 13)

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\"\"                                     (Cancel common terms)

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\"\"

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\"\"                                         (Cancel common terms)

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\"\"

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Verify:

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

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\"\" (Substitute \"\")

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  \"\"                (Add:\"\")

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

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  \"\"                                        (Add:\"\")

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Compare the values, the equation is true. The solution is \"\" .

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\"\"

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The  value of r is \"\" .

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