Final answer:
The reason that justifies the statement "2(1/2x - 5) = 20" is the Multiplication Property of Equality.
Step-by-step explanation:
The reason that justifies the statement "2(1/2x - 5) = 20" is the Multiplication Property of Equality. This property states that if we multiply or divide both sides of an equation by the same non-zero number, the equality is preserved. In this case, multiplying both sides by 2 ensures that both sides are still equal.