Here you go, i added a bit of explanation as to why i used the numbers to help you understand the method :)
Hi there!
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I believe your answer is:
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Here’s why:
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I am assuming by the infomation given that the figure is a cube.
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Hope this helps you. I apologize if it’s incorrect.
Its wrong switch the data with the mean then subtract then change the negative numbers to positive then add them together to get your Sum