Divergence and the P/B of a bank

A bank reports ROE 18%, growth 12%, cost of equity 14%. (a) Compute justified P/B on reported book. (b) A supervisory review finds that recognising true NPAs reduces book by 15% and sustainable ROE to 13%. Compute justified P/B on true book, express the price as a multiple of reported book, and the percentage fall in price. (c) Why is the fall so much larger than the 15% book write-down?