To determine the property of equality used from Step 3 to Step 4 in the sequence you provided, let's analyze the steps:
- Step 3: \( 3x - 30 = 0 \)
- Step 4: \( 3x = 30 \)
To go from \( 3x - 30 = 0 \) to \( 3x = 30 \), you are adding 30 to both sides of the equation.
Thus, the property of equality used here is the Addition Property.
So the correct response is:
B Addition Property.