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Home > CC4 > Chapter A > Lesson A.1.4 > Problem A-44

A-44.

Sylvia simplified the expressions on the Expression Comparison Mat shown below. Some of her work is shown. Are all of her moves legal? Explain. Homework Help ✎

Go through your list of legal moves and check each move made by Sylvia.

Removing the same amount from both sides is a legal move.

Flipping tiles from the subtraction region to the addition region and changing it from positive to negative is a legal move.

Removing zero pairs is a legal move.

Removing a positive tile from the (−) region and a negative tile from the (+) region is not a legal move, because they do not make a zero pair.