1. Let's clarify the problem: You want to understand how the equation for a variable $a$ is derived. 2. Typically, equations for variables like $a$ come from applying known formulas or principles to a given situation. 3. For example, if $a$ is part of a linear equation $y = ax + b$, the value of $a$ (the slope) is found using the formula: $$a = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1}$$ This formula calculates the rate of change of $y$ with respect to $x$. 4. Another example is in physics, where $a$ might represent acceleration, derived from: $$a = \frac{\Delta v}{\Delta t}$$ which is the change in velocity over time. 5. The key is to identify the context and apply the relevant formula or principle. 6. If you provide the specific equation or context, I can show step-by-step how $a$ was figured out.