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Find missing values in equivalent expressions

The learner understands that equivalent expressions have the same value even when their numbers or operations are arranged differently, and can determine a missing whole-number value in equations and expressions involving addition, subtraction, multiplication, division, parentheses, and familiar properties such as distributivity. Reasoning relies on inverse operations, place value, and preserving equality rather than treating the equal sign as a signal to calculate only the left side; formal algebraic manipulation with general variables, fractions, or negative numbers is beyond this scope.

Detailed Explanation: Find missing values in equivalent expressions

Equivalent expressions have the same value, even if they are written in different ways. To find a missing value, keep both sides equal and use an operation that helps you undo what is happening.

Example:

6×(4+)=6×4+306 \times (4+\square)=6\times4+30

Step 1: Notice the matching parts.
Both sides include 6×46\times4. The extra part on the right is 3030.

Using the distributive property,

6×(4+)=6×4+6×6\times(4+\square)=6\times4+6\times\square

So the equation becomes

6×4+6×=6×4+306\times4+6\times\square=6\times4+30

Step 2: Compare the extra parts.
After the matching 6×46\times4 parts, we need

6×=306\times\square=30

Step 3: Find the missing number.
Ask: “What number times 66 equals 3030?”

30÷6=530\div6=5

So,

=5\boxed{\square=5}

Check:

6×(4+5)=6×9=546\times(4+5)=6\times9=54

and

6×4+30=24+30=546\times4+30=24+30=54

Both sides equal 5454, so 55 is the missing value.

Learn by doing: Find missing values in equivalent expressions

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Addition & Subtraction - Balance Equation - Two Digit, Three Terms


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