Additive
Property of Equality
The formal name for the property
of equality that
allows one to add the same quantity to both sides
of an equation.
This, along with the multiplicative
property of equality, is one
of the most commonly used properties for solving equations.
Property: 
If a = b then a
+ c = b + c. 
Example: 
x – 5 = 7
(x – 5) + 5 = 7 + 5
x = 12 
