The mum of one of my daughter's friends often texts to asks me for some help, and I'm often more than happy to. However I like to know what her request is before I answer messages like today's "Hey, are you busy on Friday?". In this particular instance I do have a bit of free time but want to be selective about what I fill that with, as it's my half day off work with the kids. What can I reply so that I can find out her request without revealing what my 'free' time is?