Q 45 and 46 Schweser Book 1 Ex 2 Am different, reference, regarding

AndyNZ

Fixed Income question:
You can reference the book if you want but on 45 can some one back me up that they say that you subtract the value of the callable bond from the non-callabel which means you get a negative value and is incorrect. They then to the calculation properly but if you read the statment it is reversed. Not sure CFAI would do that.
And on 46 the motes say that “OAS will be affected by different assumptions regarding the volatility of interest rates.” in the answer. Am I missing something here? I thought it was the complete opposite……
Any help would be much appreciated. So close to life again….thanks for making my long weekend soooo fun CFA.