The property being used to solve the equation 4x + 8 = 28 is the "Additive Property of Equality." This property allows you to add or subtract the same value from both sides of an equation without changing its equality. In this case, you are subtracting 8 from both sides to isolate the variable:
4x + 8 - 8 = 28 - 8
This simplifies to:
4x = 20
Now, you can proceed to solve for x.