Final answer:
The question asks for the use of the chain rule to find a specific value or derivative. Without the actual equation or expression provided, it is difficult to provide a detailed step-by-step solution.
Step-by-step explanation:
The question is asking to use the chain rule to find a specific value or derivative. The given information states that when you know all but one variable in the expression for q, you can determine the remaining variable by using algebra. Further, it is mentioned that the chain rule for differentiation is relevant to solving this equation. However, without the actual equation or expression provided, it is difficult to provide a step-by-step solution.