Solve the Expression: 20-4+6-5 Step by Step

Q: Why can't I do all the additions first, then the subtractions?

Addition and subtraction have equal priority in order of operations, so you must work left to right. Grouping by operation type breaks this rule and will give wrong answers in many problems.

Q: What if I accidentally skip a step?

Write out each calculation step by step: $ 20 - 4 = 16 $, then $ 16 + 6 = 22 $, finally $ 22 - 5 = 17 $. This prevents errors and makes checking easier!

Q: Is there a trick to remember the left-to-right rule?

Think of it like reading a sentence - you read from left to right, and math operations with equal priority work the same way. Addition and subtraction are equal partners!

Q: What happens if I work right to left instead?

Working right to left gives $ 20 - (4 + 6 - 5) = 20 - 5 = 15 $, which is wrong! The left-to-right rule exists to ensure everyone gets the same correct answer.

Order of Operations with Mixed Addition and Subtraction

$20-4+6-5=$

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Understand the problem

$20-4+6-5=$

Step-by-step solution

To solve $20-4+6-5$ :

Start with the first operation: $20 - 4 = 16$ .
Next, add 6: $16 + 6 = 22$ .
Finally, subtract 5: $22-5=17$ .

So, the correct answer is $17$ .

Final Answer

Key Points to Remember

Essential concepts to master this topic

Rule: Work from left to right with addition and subtraction
Technique: Calculate 20 - 4 = 16, then 16 + 6 = 22, finally 22 - 5 = 17
Check: Verify each step shows correct left-to-right progression: 16 → 22 → 17 ✓

Common Mistakes

Avoid these frequent errors

Calculating all additions first, then subtractions
Don't group operations by type like (20 + 6) - (4 + 5) = 26 - 9 = 17! This ignores proper order and can give wrong results in other problems. Always work strictly left to right with addition and subtraction.

Practice Quiz

Test your knowledge with interactive questions

$$ 8 - 2 + 6 = $$

FAQ

Everything you need to know about this question

Why can't I do all the additions first, then the subtractions?

Addition and subtraction have equal priority in order of operations, so you must work left to right. Grouping by operation type breaks this rule and will give wrong answers in many problems.

What if I accidentally skip a step?

Write out each calculation step by step: $20 - 4 = 16$ , then $16 + 6 = 22$ , finally $22 - 5 = 17$ . This prevents errors and makes checking easier!

Is there a trick to remember the left-to-right rule?

Think of it like reading a sentence - you read from left to right, and math operations with equal priority work the same way. Addition and subtraction are equal partners!

How do I check my work quickly?

Trace through your steps: start with 20, subtract 4 to get 16, add 6 to get 22, subtract 5 to get 17. Each step should make sense with the previous result.

What happens if I work right to left instead?

Working right to left gives $20 - (4 + 6 - 5) = 20 - 5 = 15$ , which is wrong! The left-to-right rule exists to ensure everyone gets the same correct answer.

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