Solve the Equation: Finding the Missing Value in x - 2.2 = 2.3

Q: Why do I add 2.2 to both sides instead of subtracting it?

In the equation $ ? - 2.2 = 2.3 $, we need to undo the subtraction. The opposite of subtracting 2.2 is adding 2.2, so we add it to both sides to keep the equation balanced.

Q: What if I accidentally subtracted 2.2 from 2.3?

You'd get 0.1, which is wrong! Remember: we're not doing 2.3 - 2.2. We're finding what number minus 2.2 equals 2.3. That requires addition: 2.3 + 2.2 = 4.5.

Linear Equations with Decimal Operations

Fill in the missing value (?):

$?-2.2=2.3$

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Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Fill in the missing value (?):

$?-2.2=2.3$

Step-by-step solution

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

Step 1: Identify the given equation.
Step 2: Rearrange the equation to solve for the unknown.
Step 3: Perform the arithmetic calculation.

Now, let's work through each step:
Step 1: The given equation is $? - 2.2 = 2.3$ .
Step 2: We want to isolate the unknown (?), so we add $2.2$ to both sides of the equation. This gives us:

$? = 2.3 + 2.2$

Step 3: Perform the calculation:

$2.3 + 2.2 = 4.5$

Therefore, the solution to the problem is $4.5$ .

Final Answer

2.4

Key Points to Remember

Essential concepts to master this topic

Rule: To isolate the unknown, add the opposite of the subtracted term
Technique: Add 2.2 to both sides: ? = 2.3 + 2.2 = 4.5
Check: Substitute back: 4.5 - 2.2 = 2.3 ✓

Common Mistakes

Avoid these frequent errors

Subtracting instead of adding to isolate the variable
Don't subtract 2.2 from 2.3 to get ? = 0.1! This ignores the equation structure and gives the wrong answer. Always add the opposite of what's being subtracted from the unknown.

Practice Quiz

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FAQ

Everything you need to know about this question

Why do I add 2.2 to both sides instead of subtracting it?

In the equation $? - 2.2 = 2.3$ , we need to undo the subtraction. The opposite of subtracting 2.2 is adding 2.2, so we add it to both sides to keep the equation balanced.

What if I accidentally subtracted 2.2 from 2.3?

You'd get 0.1, which is wrong! Remember: we're not doing 2.3 - 2.2. We're finding what number minus 2.2 equals 2.3. That requires addition: 2.3 + 2.2 = 4.5.

How can I remember which operation to use?

Think: "What do I need to do to get the unknown by itself?" If something is being subtracted from the unknown, you add it to both sides. If something is being added, you subtract it from both sides.

Why is the answer 4.5 and not one of the multiple choice options?

Great observation! The explanation shows the correct calculation: 2.3 + 2.2 = 4.5. However, there seems to be an error in either the given answer choices or the explanation. Always trust your math and double-check by substituting back into the original equation.

Can I check my answer a different way?

Yes! You can think of it as: "What number minus 2.2 gives me 2.3?" Count up from 2.3: 2.3 + 2.2 = 4.5. Or substitute: $4.5 - 2.2 = 2.3$ ✓

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