1. The problem statement, all variables and given/known data 2. Relevant equations None... I think. Seems like something I should just know rather than have to work out? 3. The attempt at a solution I can do everything in this problem apart from the very first part. I thought to work out how d_a A^b transforms I'd have to start from d'_a A'^b but this must not be the case as it's the next part of the question?