Solve the Equation: Finding the Missing Number in -8 + ? = 16-(-2)

Q: Why does -(-2) become +2?

Think of it as opposite directions! If negative means "go left," then the opposite of going left 2 steps is going right 2 steps. So $ -(-2) = +2 $.

Q: How do I solve for the missing number?

First simplify the right side: $ 16-(-2) = 18 $. Then add 8 to both sides of $ -8+? = 18 $ to get $ ? = 26 $.

Q: What if I forget the double negative rule?

Practice tip: Replace $ -(-x) $ with $ +x $ immediately when you see it. Write "minus negative equals plus" as a reminder!

Q: How can I check my work?

Substitute your answer back into the original equation. Check: $ -8+26 = 18 $ and $ 16-(-2) = 18 $. Both sides equal 18, so the answer is correct!

Q: Why do we add 8 to both sides?

We want to isolate the missing number. Adding 8 cancels out the -8 on the left side: $ -8+8 = 0 $, leaving just the unknown value.

Linear Equations with Negative Numbers

$-8+?=16-(-2)$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Find the unknown

00:08 Negative times negative always equals positive

00:11 Open parentheses

00:16 Calculate the operation

00:30 Isolate the unknown

00:51 Simplify what we can

01:06 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

$-8+?=16-(-2)$

Step-by-step solution

Remember the rule:

$-(-x)=+$

Write the exercise in the appropriate form:

$-8+?=16+2$

Solve:

$-8+?=18$

Add 8 to both sides in order to zero out the left side:

$-8+?+8=18+8$

$-8+8=0$

Therefore:

$0+?=26$

$?=26$

Final Answer

$26$

Key Points to Remember

Essential concepts to master this topic

Double Negative Rule: Subtracting a negative equals adding positive
Technique: Convert $16-(-2)$ to $16+2=18$
Check: Substitute 26: $-8+26=18$ and $16-(-2)=18$ ✓

Common Mistakes

Avoid these frequent errors

Treating double negative as subtraction
Don't calculate 16-(-2) as 16-2=14! This ignores the negative sign rule and gives the wrong target value. Always remember that subtracting a negative number means adding the positive version.

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 -(-2) become +2?

Think of it as opposite directions! If negative means "go left," then the opposite of going left 2 steps is going right 2 steps. So $-(-2) = +2$ .

How do I solve for the missing number?

First simplify the right side: $16-(-2) = 18$ . Then add 8 to both sides of $-8+? = 18$ to get $? = 26$ .

What if I forget the double negative rule?

Practice tip: Replace $-(-x)$ with $+x$ immediately when you see it. Write "minus negative equals plus" as a reminder!

How can I check my work?

Substitute your answer back into the original equation. Check: $-8+26 = 18$ and $16-(-2) = 18$ . Both sides equal 18, so the answer is correct!

Why do we add 8 to both sides?

We want to isolate the missing number. Adding 8 cancels out the -8 on the left side: $-8+8 = 0$ , leaving just the unknown value.

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