I'll do the first five problems to get you started.
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Problem 1
Subtraction can be thought of as adding a negative.
So -3 - 6 is the same as -3 + (-6)
We can think of an example involving money
-3 means we're 3 dollars in debt. Then -6 means we go 6 dollars further into debt. Therefore, the total debt is -3 + (-6) = -9 so overall we're 9 dollars in debt.
Answer: -3 + (-6)
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Problem 2
When subtracting a negative, the two will cancel out to form a positive. This is because negatives are opposite in nature. Two opposites undo one another.
So with all that in mind, something like 10 - (-4) will become 10 + 4
Answer: 10 + 4
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Problem 3
It's the same idea as the previous problem, but we're dealing with different numbers of course.
Answer: 7 + 2
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Problem 4
We'll use the ideas mentioned in problem 1. There's not much further to explain here.
Answer: -4 + (-8)
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Problem 5
Refer back to either problem 2 or problem 3 for a similar example. The negatives will cancel to form a positive.
Answer: -8 + 4