ANSWER
The substitution property of equality.
Step-by-step explanation
We know that:
![12x = 60](https://img.qammunity.org/2020/formulas/mathematics/middle-school/eomat0jxipmo2xbl78gloein14bzbdp51g.png)
and that
![x = 5](https://img.qammunity.org/2020/formulas/mathematics/high-school/q47q2r4ttysyvhwrvmu4tvjt4greotllkp.png)
Since x=5 or 5=x , we can substitute x for 5 wherever we see x in the given equation.
When we do that, we obtain;
![12 \bullet \: 5 = 60](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6slxsf5nlmcq1uiumpf7x8q2wj6cn0syba.png)
This is what we refer to as the substitution property of equality.