Solve the Expression: 7×3+8-4-7 Using Order of Operations

Order of Operations with Mixed Arithmetic

73+847=? 7\cdot3+8-4-7=\text{?}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:07 Let's solve this math expression together.
00:10 Remember! Do multiplication and division before addition and subtraction.
00:17 Also, start with the operation on the left side first.
00:27 Great! This is how we find the solution.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

73+847=? 7\cdot3+8-4-7=\text{?}

2

Step-by-step solution

According to the rules of the order of operations, multiplication and division precede addition and subtraction.

We isolate the multiplication exercise in parentheses and solve.

(7×3)=21 (7\times3)=21

Now, the exercise we're left with is: 21+847= 21+8-4-7=

We solve the exercise from left to right. We isolate the next part of the expression with parentheses to avoid confusion(21+8)=29 (21+8)=29

Now, the exercise obtained is: 2947= 29-4-7=

We continue solving from left to right and isolate the next part of the expression in parentheses.

(294)=25 (29-4)=25

Now, the expression obtained is: 257=18 25-7=18

3

Final Answer

18

Key Points to Remember

Essential concepts to master this topic
  • PEMDAS Rule: Multiplication first, then addition and subtraction from left to right
  • Technique: Calculate 7×3=21 7 \times 3 = 21 first, then 21+847 21+8-4-7
  • Check: Verify step by step: 21+8=29, 29-4=25, 25-7=18 ✓

Common Mistakes

Avoid these frequent errors
  • Solving operations from left to right without considering PEMDAS
    Don't solve 7+3=10 then continue left to right = wrong answer of 5! This ignores multiplication priority and breaks the order of operations. Always complete multiplication before any addition or subtraction.

Practice Quiz

Test your knowledge with interactive questions

Solve the following problem:

\( 15\times2\times8= \)

FAQ

Everything you need to know about this question

Why can't I just solve from left to right like reading?

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Mathematics has a specific order that's different from reading! Without PEMDAS rules, the expression 2+3×4 2+3 \times 4 could mean either 20 or 14 - we need consistent rules to avoid confusion.

What does PEMDAS stand for again?

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Parentheses, Exponents, Multiplication and Division (left to right), Addition and Subtraction (left to right). Remember: Please Excuse My Dear Aunt Sally!

Do I need parentheses to show my work?

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Adding parentheses like (7×3)+847 (7 \times 3) + 8 - 4 - 7 is a great strategy to show which operation you're doing first! It helps prevent mistakes and makes your work clearer.

What if I get a different answer than 18?

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Double-check each step: 7×3=21 7 \times 3 = 21 , then 21+8=29 21 + 8 = 29 , then 294=25 29 - 4 = 25 , finally 257=18 25 - 7 = 18 . Slow down and verify each calculation!

Are multiplication and division really equal priority?

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Yes! Multiplication and division have equal priority, so you work from left to right when they appear together. Same rule applies to addition and subtraction - they're equal priority too.

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