The identity property of addition states that if we sum zero to a number, the result will be the same number.
When we have the equation
[tex]18+m=18[/tex]And evaluate at m = 0, we just substitute m in the equation for our value
[tex]\begin{cases}18+m=18 \\ m=0\end{cases}\Rightarrow18+0=18[/tex]And this is the definition of the identity property.
