Final answer:
To keep the equation 5x - 26 = 84 balanced, you should choose option C, which is to add 26 to both sides.
Step-by-step explanation:
Balancing chemical equations is a fundamental skill in chemistry. A balanced chemical equation ensures that the number of atoms of each element is the same on both the reactant and product sides of the equation. The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction, so the number of atoms must be the same before and after the reaction.
To keep the equation 5x - 26 = 84 balanced, you should choose option C, which is to add 26 to both sides. By adding 26 to both sides of the equation, the equation will remain balanced because both sides will undergo the same operation, maintaining the equality.