Solve 15-(-4): Understanding Double Negative Subtraction

Q: Why does subtracting a negative become addition?

Think of it this way: if you remove a debt (negative), you're actually gaining money (positive)! So $ 15-(-4) $ means "15, then remove negative 4" which gives you 15+4.

Q: How do I remember the double negative rule?

Use the phrase "two negatives make a positive". When you see $ -(-4) $, the first negative (subtraction) and second negative (the number) combine to make positive 4.

Q: What's the difference between 15-4 and 15-(-4)?

$ 15-4 = 11 $ (regular subtraction), but $ 15-(-4) = 19 $ (subtracting negative = adding positive). The extra negative sign completely changes the operation!

Q: Can I use a number line to visualize this?

Absolutely! Start at 15 on the number line. Instead of moving 4 steps left (which would be -4), you move 4 steps right because you're subtracting a negative. You land on 19.

Q: Will this rule work for bigger numbers too?

Yes! The rule always works. Whether it's $ 100-(-25) = 125 $ or $ 7-(-3) = 10 $, subtracting any negative number means adding its positive version.

Integer Subtraction with Double Negatives

$15-(-4)=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:03 Negative times negative always equals positive

00:09 Open parentheses

00:12 Calculate

00:15 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$15-(-4)=$

Step-by-step solution

Let's remember the following law:

$-(-x)=+$

Now let's write the exercise in the appropriate form:

$15+(4)=19$

Final Answer

$19$

Key Points to Remember

Essential concepts to master this topic

Rule: Subtracting a negative number means adding its positive
Technique: Convert 15-(-4) to 15+4 = 19
Check: Two negatives make positive: -(-4) = +4 ✓

Common Mistakes

Avoid these frequent errors

Treating double negatives as regular subtraction
Don't compute 15-(-4) as 15-4 = 11! This ignores the negative sign rule and gives the wrong answer. Always remember that subtracting a negative number equals adding the positive number.

Practice Quiz

Test your knowledge with interactive questions

a is negative number.

b is negative number.

What is the sum of a+b?

FAQ

Everything you need to know about this question

Why does subtracting a negative become addition?

Think of it this way: if you remove a debt (negative), you're actually gaining money (positive)! So $15-(-4)$ means "15, then remove negative 4" which gives you 15+4.

How do I remember the double negative rule?

Use the phrase "two negatives make a positive". When you see $-(-4)$ , the first negative (subtraction) and second negative (the number) combine to make positive 4.

What's the difference between 15-4 and 15-(-4)?

$15-4 = 11$ (regular subtraction), but $15-(-4) = 19$ (subtracting negative = adding positive). The extra negative sign completely changes the operation!

Can I use a number line to visualize this?

Absolutely! Start at 15 on the number line. Instead of moving 4 steps left (which would be -4), you move 4 steps right because you're subtracting a negative. You land on 19.

Will this rule work for bigger numbers too?

Yes! The rule always works. Whether it's $100-(-25) = 125$ or $7-(-3) = 10$ , subtracting any negative number means adding its positive version.

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