The expression is .
(Apply commutative property of addition: )
(Subtract: )
The standard form of the expression is .
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
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.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=7e51988a4df4bb47787097a4afeffb89.png\")
(Apply commutative property of addition: ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=7aaddae65b90f9825695c36c245deeb9.png\")
)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0e1a487e59cc2338ad2c368e50fda148.png\")
(Subtract: ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0e2031988fed01297ab8400efb567b73.png\")
)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=96b61a8bf859aabe9140bfadf862bc91.png\")
(Apply commutative property of addition: ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=942b9b9371942849950ea3aa13cf2428.png\")
)![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
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.