Answer:
substitution Property of equality is the idea that if x=y, you can then plug x in for y in any equation that y is in. This is helpful if you have two equations where you need to solve for two different variables because you can find that x=y, and then when you plug it into an equation for y, you end up with some form of x=x, which can be easily solved by using addition, subtraction, multiplication and division to get both x to the same side of the equation, and then getting everything else to the other side.
Explanation: