Final answer:
It's impossible to determine whether to apply a reflection across line k or a translation along vector ū to the figure ADEF without more context. The order of transformations is dependent on specific instructions or the intended result.
Step-by-step explanation:
The order in which transformations like reflection and translation are applied to a geometric figure can affect the final position of the figure. When the question is about deciding which transformation should be applied first to the figure ADEF, the student needs to consider the context or the objective of the transformation to make an appropriate decision. Without additional context, it is impossible to definitively determine whether a reflection across line k or a translation along vector ū should be applied first. Generally, the sequence of transformations follows a specific set of instructions or desired outcomes, so it's important to follow the order given in the problem or to understand the desired final position of the figure.