If doing X by Y is possible and will achieve Q, then the best way to respond to these questions is either of: 1. To do Q that way you would to <solution, or at

If doing X by Y is possible and will achieve Q, then the best way to respond to these questions is either of: 1. To do Q that way you would to <solution, or at least pointers to how to find the solution elsewhere> but you will likely it far more efficient/easy/whatever to do <something else> instead. 2. Q can be achieved far more efficient/easy/whatever by doing <alternative>, but if you are stuck with using Y then try <solution or pointers as above>. Of course this relies on you correctly deriving that they are trying to achieve Q, or them explicitly stating the fact. Maybe instead they are trying to get to K.