The expression is .
(Commutative property: a + b = b + a)
(Add: 13 + 3 = 16)
(Subtract: )
The value of the expression is 8.
![\"\"](\"/userfiles/image/Library/Commutative_Property_of_addition.gif\")
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
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.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=fb41a8a51e22d272fdf4f6dee7f87e05.png\")
(Commutative property: a + b = b + a) ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0da6ff2445b668c6432e218c98a668d2.png\")
(Add: 13 + 3 = 16)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=8f71fbbfe8c58f5465acf04fa04cd7db.png\")
(Subtract: ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=3473570074885ef419ccf912378321d7.png\")
)![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")