Please help with the following question:

You own a gas pipeline that requires no maintenance or other operating expenses and will produce $2 million of revenue next year. Unfortunately, the volume of gas transmitted through the pipeline is expected decline by 4% per year. The discount rate is 11%.

a) if the pipeline lasts forever, what is it worth today?

b) if the pipeline were to be abandoned after 20 years, what would it be worth today?