1. Let's clarify the problem: You want to understand what formula was used in a certain math problem. 2. Typically, formulas depend on the context, such as algebraic equations, geometry, or physics. 3. For example, if the problem involves solving a linear equation like $ax + b = 0$, the formula used is $x = -\frac{b}{a}$. 4. If you provide the specific problem or equation, I can explain the exact formula and steps used. 5. Please share the original problem or the formula you are referring to, so I can help you better.