Question

Which number line best shows how to solve −8 − (−2)? (5 points)

Answer 1

Answer: Choice A

Arrow from 0 to -8 (pointing left). Another arrow from -8 to -6 (pointing right)

See diagram below

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Explanation:

Let's think of this in terms of money. Writing -8 means we are 8 dollars in debt. Since -8 is listed first, this means we start at 0 and go 8 units to the left along the number line, to land on -8.

Then we'll go 2 units to the right to land ultimately at -6. This is because of the "-(-2)" portion, which is the same as "+2". Subtracting a negative is the same as adding. The two negatives cancel each other out.

Going back to the money example, if we have a balance of -8 (we're 8 dollars in debt) and taking away 2 IOU notes means we're 6 dollars in debt. Subtracting a negative can be thought of as taking away debt.

Side note: If we had -8-2, then we would go 2 units to the left of -8 to land on -10 instead.