Solve (+7)-(-6.7): Addition and Subtraction with Signed Decimals

Q: Why does subtracting a negative number make the answer bigger?

Think of it as removing debt! If you have $7 and someone removes a debt of $6.70 from you, you end up with more money: $ 7+6.70=13.70 $. Subtracting negative means adding positive.

Q: How do I remember when to add or subtract?

Use the rule: two negatives make a positive. When you see $ -(-x) $, the minus signs cancel out to become $ +x $. So $ -(-6.7) = +6.7 $.

Q: What if I had (+7) + (-6.7) instead?

That would be addition of a negative, which equals subtraction: $ 7+(-6.7)=7-6.7=0.3 $. Notice how different operations with negatives give completely different answers!

Q: Do I need to worry about the decimal alignment?

Yes! When adding $ 7.0+6.7 $, line up the decimal points vertically. This ensures you add tenths to tenths and ones to ones correctly.

Q: Can I check my answer another way?

Absolutely! Try thinking: "What number minus 6.7 equals 7?" Since $ 13.7-6.7=7 $, you know $ 13.7 $ is correct.

Subtracting Negative Numbers with Mixed Decimals

$(+7)-(-6.7)=$

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Step-by-step video solution

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00:00 Solve

00:03 Negative times negative always equals positive

00:07 And this is the solution to the question

Step-by-step written solution

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Understand the problem

$(+7)-(-6.7)=$

Step-by-step solution

Let's remember the rule:

$-(-x)=+x$

Now let's write the exercise in the appropriate form and solve it:

$7+6.7=13.7$

Final Answer

$13.7$

Key Points to Remember

Essential concepts to master this topic

Rule: Subtracting a negative equals adding the positive
Technique: Convert $(+7)-(-6.7)$ to $7+6.7$
Check: Verify that $7+6.7=13.7$ is correct ✓

Common Mistakes

Avoid these frequent errors

Keeping the subtraction operation when there's a negative sign
Don't calculate $7-6.7=0.3$ ! This ignores the negative sign in front of -6.7 and gives the wrong answer. Always change subtraction of negative to addition: $(+7)-(-6.7)=7+6.7=13.7$ .

Practice Quiz

Test your knowledge with interactive questions

$$ -5-(-2)= $$

FAQ

Everything you need to know about this question

Why does subtracting a negative number make the answer bigger?

Think of it as removing debt! If you have $7 and someone removes a debt of $6.70 from you, you end up with more money: $7+6.70=13.70$ . Subtracting negative means adding positive.

How do I remember when to add or subtract?

Use the rule: two negatives make a positive. When you see $-(-x)$ , the minus signs cancel out to become $+x$ . So $-(-6.7) = +6.7$ .

What if I had (+7) + (-6.7) instead?

That would be addition of a negative, which equals subtraction: $7+(-6.7)=7-6.7=0.3$ . Notice how different operations with negatives give completely different answers!

Do I need to worry about the decimal alignment?

Yes! When adding $7.0+6.7$ , line up the decimal points vertically. This ensures you add tenths to tenths and ones to ones correctly.

Can I check my answer another way?

Absolutely! Try thinking: "What number minus 6.7 equals 7?" Since $13.7-6.7=7$ , you know $13.7$ is correct.

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