Solve for ?: (45-22)×19+25÷5+?×3=82 Order of Operations

Order of Operations with Missing Variables

Calculate the missing number in the equation:

(4522)×19+25 ⁣:5+?×3=82 (45-22)\times19+25\colon5+?\times3=82

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:13 Let's start by focusing on the expression inside the parentheses.
00:30 Next, we do the multiplication and division steps.
00:47 Keep going as we solve the problem step by step.
00:57 Now subtract four hundred forty-two from both sides to isolate the variable.
01:15 Finally, divide both sides by three. And that's how we solve this problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Calculate the missing number in the equation:

(4522)×19+25 ⁣:5+?×3=82 (45-22)\times19+25\colon5+?\times3=82

2

Step-by-step solution

We solve the exercise in parentheses:

23×19+25 ⁣:5+?×3=82 23\times19+25\colon5+?\times3=82

We place the multiplication and division exercises inside parentheses:

(23×19)+(25 ⁣:5)+?×3=82 (23\times19)+(25\colon5)+?\times3=82

We solve the exercise in parentheses:

437+5+?×3=82 437+5+?\times3=82

We simplify:

442+?×3=82 442+?\times3=82

We swap sections:

?×3=82442 ?\times3=82-442

?×3=360 ?\times3=-360

We divide by 3

?=120 ?=-120

3

Final Answer

?=120 ?=-120

Key Points to Remember

Essential concepts to master this topic
  • Rule: Follow PEMDAS - parentheses, then multiplication/division left to right
  • Technique: Calculate (45-22)×19 = 23×19 = 437, then 25÷5 = 5
  • Check: Substitute ?=-120: 437+5+(-120)×3 = 442-360 = 82 ✓

Common Mistakes

Avoid these frequent errors
  • Solving left to right without following order of operations
    Don't solve 45-22+19×25÷5 from left to right = wrong operations order! This ignores multiplication and division priority, giving completely wrong results. Always follow PEMDAS: parentheses first, then multiplication and division before addition and subtraction.

Practice Quiz

Test your knowledge with interactive questions

\( 20\div(4+1)-3= \)

FAQ

Everything you need to know about this question

Why do I get the wrong answer when I solve from left to right?

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Order of operations matters! You must do multiplication and division before addition and subtraction. Otherwise, you're solving a completely different equation.

What does the colon symbol mean in 25÷5?

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The colon (:) means division, just like the ÷ symbol. So 25 ⁣:5=25÷5=5 25\colon5 = 25÷5 = 5 .

How do I isolate the unknown variable ?

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After following order of operations, you'll have a simple equation like ?×3=360 ?×3 = -360 . Then just divide both sides by 3 to get ?=120 ? = -120 .

Can the answer be negative?

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Yes! Negative numbers are perfectly valid answers. In this problem, ?=120 ? = -120 because (120)×3=360 (-120)×3 = -360 .

What if I forget to do parentheses first?

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You'll get the wrong answer! Always solve what's in parentheses first: (4522)=23 (45-22) = 23 , then multiply by 19.

How can I check if my final answer is correct?

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Substitute your answer back into the original equation. If the left side equals 82, you're right! For example: 23×19+5+(120)×3=437+5360=82 23×19+5+(-120)×3 = 437+5-360 = 82

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