Solve the Equation: Finding the Value of △ in 78 + △ = 80

Basic Linear Equations with Subtraction

Determine the numerical value of the triangle:

78+=80 78+\triangle=80

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Determine the numerical value of the triangle:

78+=80 78+\triangle=80

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Recognize the format of the provided equation.
  • Apply the appropriate arithmetic operation to isolate \triangle.
  • Perform the necessary calculations.

Now, let's work through each step:
Step 1: The given equation is 78+=80 78 + \triangle = 80 . We are tasked with finding the value of \triangle.
Step 2: To find \triangle, rearrange the equation to solve for \triangle:
=8078\triangle = 80 - 78.
Step 3: Subtract the known value from the total to isolate \triangle:
=8078=2\triangle = 80 - 78 = 2.

Hence, the solution to the problem is =2\triangle = 2.

3

Final Answer

2 2

Key Points to Remember

Essential concepts to master this topic
  • Isolation Rule: Move the known number to opposite side using subtraction
  • Technique: From 78 + △ = 80, subtract 78: △ = 80 - 78 = 2
  • Check: Substitute back into original equation: 78 + 2 = 80 ✓

Common Mistakes

Avoid these frequent errors
  • Adding instead of subtracting to isolate the variable
    Don't add 78 to both sides giving △ = 80 + 78 = 158! This makes the equation unbalanced because you're moving the wrong direction. Always subtract the number that's being added to the variable.

Practice Quiz

Test your knowledge with interactive questions

If we have 67 blocks in total, how many blocks will remain if we remove 5 tens and 4 ones?

FAQ

Everything you need to know about this question

Why do I subtract 78 from both sides instead of adding?

+

Since 78 is being added to △, you need to do the opposite operation (subtraction) to cancel it out. Think of it like undoing what's already there!

What if the triangle was on the right side of the equation?

+

The process is exactly the same! Whether it's 78+=80 78 + \triangle = 80 or 80=78+ 80 = 78 + \triangle , you still subtract 78 from both sides.

How do I remember which operation to use?

+

Use the opposite operation: if something is being added (+), subtract it (-). If something is being subtracted (-), add it (+). It's like doing the reverse!

Can I check my answer a different way?

+

Yes! You can also think: "What number plus 78 equals 80?" Count up from 78 to 80, and you get 2. Both methods should give the same answer.

What if I get a negative number as my answer?

+

Negative answers are completely normal! For example, if you had 90+=85 90 + \triangle = 85 , then =5 \triangle = -5 . Always check by substituting back.

🌟 Unlock Your Math Potential

Get unlimited access to all 18 Natural Numbers around 100 questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations