Balance Addition and Subtraction Equations up to 20

Learn to Balance Addition and Subtraction Equations up to 20

So far, you've added and subtracted a lot of numbers. You've also balanced addition and subtraction equations! π

Now, let's learn to balance equations with both addition AND subtraction in them! π€

Look at these two equations. π

14 - 3 = 11
6 + 5 = 11

What do they have in common? π€

Very good! π They both equal 11.

When two expressions (addition or subtraction) have the same value, we can write them on either side of an equal sign.

Each expression will be half of a larger equation:

β The equals sign (=) tells us that both sides of the equation have the same value.

When both sides of the equal sign have the same value, we say the equation is balanced!

π€ Is the following equation balanced?

13 + 4 = 20 - 3

π To see, let's simplify both sides of the equation separately.

13 + 4 = 17

and

20 - 3 = 17

Both sides of the equation have a value of 17.

So yes, the equation is balanced!__

16 - 7 = ? + 1

How do we find the missing number? π€

You got it! π

To find the missing number in an equation, first simplify the side that is complete. It's the side without any missing numbers.

Let's try it out! π€

In our example, which side is complete?

Correct!

16 - 7 = ?

π Let's simplify this subtraction operation down to a value.

16 - 7 = 9

Good job! π

We know that 9 is the answer to the other side as well.

Now, we can write an easier equation to solve:

? + 1 = 9

What is missing, the part or the whole?

π This addition equation tells us that 9 has been split into 2 parts. One part is missing!

What is the missing number? π€

Nice work! π The missing number is 8.

8 + 1 = 9

Let's put 8 in our original equation:

16 - 7 = 8 + 1

Great job! You balanced the equation. π

π Let's try another example.

Example 1

? - 4 = 3 + 3

How will you start? π€

Very good!

β We simplify the complete side.

3 + 3 = 6

Now, rewrite the simplified equation.

? - 4 = 6

π€ What's the next step?

That's right, we think about the whole-part model.

π€ This subtraction equation tells us that 4 has been taken away from a bigger number to get 6.

What's the missing number? π€

Great job! π The missing number is 10.

10 - 4 = 6

Let's put it back in our original equation:Β

10 - 4 = 3 + 3

Let's try one more!

Example 2

13 + 2 = 19 - ?

First, simplify the side you can!

13 + 2 = 15

Now, use this answer to find the missing number.

15 = 19 - ?

This subtraction equation tells us that a part of 19 has been taken away to get 15.

What is the missing number? π€

You got it! π€ The missing number is 4.

19 - 4 = 15

Let's put 4 in our original equation:

13 + 2 = 19 - 4

Great job! π You balanced the equation.

Watch and Learn

Now go ahead and try practice. π

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