Solve the Arithmetic Expression: 20 - 5 + 2

Q: Why can't I add 5 + 2 first since it's easier?

Even though 5 + 2 = 7 is simple, the order of operations requires you to work left to right for addition and subtraction. Changing the order gives you 13 instead of the correct answer 17.

Q: What if there were parentheses around 5 + 2?

If the problem was $ 20 - (5 + 2) $, then you would add first! Parentheses always come before left-to-right operations.

Q: How do I remember the correct order?

For expressions with only addition and subtraction, think of reading a book - you go from left to right. Calculate each operation as you encounter it.

Q: What's the difference between 20 - 5 + 2 and 20 - (5 + 2)?

Without parentheses: $ 20 - 5 + 2 = 17 $With parentheses: $ 20 - (5 + 2) = 20 - 7 = 13 $The parentheses completely change the answer!

Q: Can I use a calculator for this?

Yes! But make sure to enter the expression exactly as written: 20 - 5 + 2. Most calculators follow the correct order of operations automatically.

Order of Operations with Mixed Operations

Solve:

$20 - 5 + 2$

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Step-by-step written solution

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Understand the problem

Solve:

$20 - 5 + 2$

Step-by-step solution

First, subtract 5 from 20:

$20 - 5 = 15$

Then, add 2:

$15 + 2 = 17$

So, the correct answer is 17.

Final Answer

Key Points to Remember

Essential concepts to master this topic

Rule: Work left to right for addition and subtraction
Technique: First calculate 20 - 5 = 15, then 15 + 2
Check: Substitute back: 20 - 5 + 2 equals 17 ✓

Common Mistakes

Avoid these frequent errors

Adding and subtracting in wrong order
Don't calculate 5 + 2 = 7 first, then 20 - 7 = 13! This ignores left-to-right order and gives the wrong answer. Always work from left to right when operations have equal priority.

Practice Quiz

Test your knowledge with interactive questions

$$ 8 - 2 + 6 = $$

FAQ

Everything you need to know about this question

Why can't I add 5 + 2 first since it's easier?

Even though 5 + 2 = 7 is simple, the order of operations requires you to work left to right for addition and subtraction. Changing the order gives you 13 instead of the correct answer 17.

What if there were parentheses around 5 + 2?

If the problem was $20 - (5 + 2)$ , then you would add first! Parentheses always come before left-to-right operations.

How do I remember the correct order?

For expressions with only addition and subtraction, think of reading a book - you go from left to right. Calculate each operation as you encounter it.

What's the difference between 20 - 5 + 2 and 20 - (5 + 2)?

Without parentheses: $20 - 5 + 2 = 17$
With parentheses: $20 - (5 + 2) = 20 - 7 = 13$
The parentheses completely change the answer!

Can I use a calculator for this?

Yes! But make sure to enter the expression exactly as written: 20 - 5 + 2. Most calculators follow the correct order of operations automatically.

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