The expression is .
(Substitute 4 and 8 for a and b)
(Multiply: )
= 20 (Add: 12 + 8 = 20)
The value of expression is 20.
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
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.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=ab47f03fde0678356a6090fc1050916a.png\")
(Substitute 4 and 8 for a and b) ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=4cb47d7b59d36449048ea3dc829a7f14.png\")
(Multiply: ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=fecebd3421feafe5e2f0bf89b077c0db.png\")
)![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")