Answers:
First box = 864
Second box = 3136
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Explanation:
The weird looking E symbol is the greek uppercase letter sigma which stands for "sum". You'll be adding everything in the x^2 column to find that 64+144+256+400 = 864, which is already done for you in the table (as the 864 is at the bottom of the second column, in the "total" row).
In short, you just copy the 864 into the first box.
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For the second box, you'll square the 56 to get 3136
This is because the table shows that adding up all the x values leads to 56
(8+12+16+20 = 56)
So that means and