Solve 300-(80-120): Order of Operations with Integer Subtraction

Q: Why do I get a negative number inside the parentheses?

When you subtract a larger number from a smaller number, you always get negative! In this case, $ 80 - 120 = -40 $ because 80 is less than 120.

Q: How does subtracting a negative become addition?

Think of it as removing a debt! Subtracting negative 40 is like removing a debt of 40, which actually adds 40 to your total. So $ 300 - (-40) = 300 + 40 $.

Q: What if I accidentally calculated 300-80-120 instead?

You'd get 100, which is wrong! This happens when you ignore the parentheses. Remember: parentheses create a separate calculation that must be done first.

Q: How can I remember the order of operations?

Use PEMDAS: Parentheses, Exponents, Multiplication/Division, Addition/Subtraction. Parentheses always come first, no matter what!

Q: Why is this different from 300-80-120?

The parentheses make $ (80-120) $ into one number: -40. So you're really calculating $ 300 - (-40) $, not three separate subtractions!

Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:03 When opening parentheses, minus times minus always equals plus

00:10 We will use this formula in our exercise

00:15 Let's solve according to the order of operations from left to right

00:24 We will use long addition

00:32 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution

1

Understand the problem

$300-(80-120)=$

2

Step-by-step solution

To solve the expression $300 - (80 - 120)$ , we'll follow these steps:

Step 1: Evaluate the expression within the parentheses.
Step 2: Substitute the evaluated result into the overall expression.
Step 3: Perform arithmetic operations to find the solution.

Now, let's evaluate the expression:

Step 1: Inside the parentheses, we calculate:

$80 - 120 = -40$

Step 2: Substitute this result back into the main expression, which becomes:

$300 - (-40)$

Step 3: Address the subtraction of a negative number, which effectively becomes addition:

$300 + 40 = 340$

Therefore, the solution to the problem is $340$ .

3

Final Answer

340

Key Points to Remember

Essential concepts to master this topic

Rule: Always solve expressions inside parentheses first before other operations
Technique: When subtracting negatives like 300-(-40), change to addition: 300+40
Check: Verify 80-120=-40, then 300-(-40)=340 matches the given answer ✓

Common Mistakes

Avoid these frequent errors

Ignoring parentheses and calculating left to right
Don't calculate 300-80-120=100! This ignores order of operations and gives the wrong answer. The parentheses change everything because 80-120=-40 first. Always solve parentheses before moving to other operations.

Practice Quiz

Test your knowledge with interactive questions

$70:(14\times5)=$

FAQ

Everything you need to know about this question

Why do I get a negative number inside the parentheses?

+

When you subtract a larger number from a smaller number, you always get negative! In this case, $80 - 120 = -40$ because 80 is less than 120.

How does subtracting a negative become addition?

+

Think of it as removing a debt! Subtracting negative 40 is like removing a debt of 40, which actually adds 40 to your total. So $300 - (-40) = 300 + 40$ .

What if I accidentally calculated 300-80-120 instead?

+

You'd get 100, which is wrong! This happens when you ignore the parentheses. Remember: parentheses create a separate calculation that must be done first.

How can I remember the order of operations?

+

Use PEMDAS: Parentheses, Exponents, Multiplication/Division, Addition/Subtraction. Parentheses always come first, no matter what!

Why is this different from 300-80-120?

+

The parentheses make $(80-120)$ into one number: -40. So you're really calculating $300 - (-40)$ , not three separate subtractions!

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Solve 300-(80-120): Order of Operations with Integer Subtraction

Parentheses with Negative Number Operations

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