Interest swap quotes from Intermediary

Hi John, In your lecture related to Interest swaps, I could very well understand the concept. However, I could not find how the interest swap calculations are performed in the case of intermediaries like Bank. I could find questions/separate topic in Kaplan which reads as follows- "Calculation involving swap quotes from intermediaries". In this topic they have discussed about 'ask rate' & 'bid rate' followed by illustration & questions. I could not understand their working. Could you please confirm if it is examinable, if yes, please explain. Thankyou