It appears that you want to manipulate the equation \( x_{15} = 6 \) to isolate \( x_{15} \). However, as it stands, \( x_{15} = 6 \) simply states that \( x_{15} \) is equal to 6, and there are no other operations or missing values to manipulate.
If \( x_{15} \) represents an expression that requires simplification or inversion, please provide that expression, and I can help with the calculations.
In the case that you are looking for how to express \( x_{15} \) by reversing the operation (in this context, there isn't an operation to reverse since it is already equated), it is simply understood that:
- Since \( x_{15} = 6 \), there are no missing values to find; the solution is straightforward.
If you have a different equation or context in mind, please clarify, and I’ll be happy to assist!