### Video Transcript

Complete the expression, stating which property is being used: 43 plus something equals nine plus 43.

To work out the missing number, let’s first consider the right-hand side. The right-hand side states nine plus 43. Well adding 43 to nine gives us 52.

And this means that the left-hand side must also be equal to 52. If we let the missing number equal 𝑥, then we have 43 plus 𝑥 equals 52. Subtracting 43 from both sides of the equation gives us 𝑥 equals nine, as 52 minus 43 equals nine.

Therefore, the missing number equals nine. 43 plus nine is equal to nine plus 43. This is due to the commutative property, which states 𝑎 plus 𝑏 is equal to 𝑏 plus 𝑎.

This means that it doesn’t matter which order we add two numbers, the answer will always be the same. In this case, 43 plus nine equals 52 and nine plus 43 equals 52.