ROE tree and asset quality

A bank has NIM 3.8%, fee income 1.1%, operating cost 2.3% and credit cost 0.5%, all of average assets; tax rate 25.17%; average assets/equity 9.5; cost of equity 13.5%; book growth 10%. (a) Compute ROA, ROE and the justified P/B. (b) Credit cost rises permanently to 1.2% and the retention ratio is unchanged. Compute the new ROE, growth and P/B. (c) Instead the shock lasts two years, after which ROE and growth return to (a). Compute P/B. (d) The bank's GNPA is 2.5% with PCR 75%. Compute NNPA. Raising PCR to 85% with loans equal to 7 times equity costs what fraction of book after tax?