The equation is 

             (Subtract 90 from each side)

                         (Apply Additive inverse property: 90-90= 0)

                                (Subtract:    )

Check:

To check the solution, substitute  in original equation.

                              (Add:)

The statement is true.

 Graph the solution on number line.

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• First draw a number line.
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• Mark a dot at -31 on  the number line.
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The value of .