Final answer:
The property being used in the given equation is the additive inverse property. When we add a number to its additive inverse, the result is always zero.
Step-by-step explanation:
The property being used in the given equation is the additive inverse property.
The additive inverse property states that for any number a, there exists a number -a such that a + (-a) = 0. This means that when we add a number to its additive inverse, the result is always zero.
In the given equation, we can see that 6p + 3p on one side is being combined with 5 - 3p + 3p on the other side. By using the additive inverse property, we can rearrange the terms to simplify the equation: 6p + 3p = (5 - 3p) + 3p = 5 + (0).