Question

The sum of an unknown and eight is twenty. What is the unknown?
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Answer 1

indicates subtraction

20 - 8 = 12

Answer 2

12

Explanation:

We can transform this into an equation in which the unknown will be represented by x. The word "sum" shows us that we are using addition, and we already know that we are adding 8 to the unknown (or x) and the answer to the equation is 20. Lets put this into a number equation now.

x+8=20

Now we just undo the equation. We have to subtract 8 from both sides.

x+8(-8)=20(-8)

x=12

The answer is 12. :) have a good day!