1. The problem is to find the radius $r$ of the 2nd blade given the equation $r(2 + \text{theatre}) = 60$. 2. We start with the equation: $$r(2 + \text{theatre}) = 60$$ 3. To isolate $r$, divide both sides by $(2 + \text{theatre})$: $$r = \frac{60}{2 + \text{theatre}}$$ 4. This formula shows that the radius $r$ depends on the value of $\text{theatre}$. Once $\text{theatre}$ is known, substitute it into the formula to find $r$. 5. This approach is valid because multiplication and division are inverse operations, allowing us to solve for $r$ easily. Final answer: $$r = \frac{60}{2 + \text{theatre}}$$