1. The problem states that the variable $r$ is unknown, and we need to find its value. 2. To solve for $r$, we need an equation or context involving $r$. Since none is provided, let's assume a general approach: if you have an equation like $ar + b = c$, you can isolate $r$ by subtracting $b$ from both sides and then dividing by $a$. 3. The formula to solve for $r$ in a linear equation $ar + b = c$ is: $$r = \frac{c - b}{a}$$ 4. Without specific values or an equation, we cannot find a numerical value for $r$. Please provide the equation or context where $r$ appears.