What Simon said ^^? How many houses can you see. You’ll need a very long pole. The higher up the building the harder and slower the cleaning will be so factor that into the price too.
This alone would put me off as a newbie.
I have a 40' and I doubt I could reach the top floor with it. I would check out it my pole would reach the top windows before I quoted. If it didn't or I had to buy a pole especially for the job I would decline it.
Quote, get the job and then they cancel after a couple of cleans. He will now have a 50' pole he will hardly every use.
Using an old SLX40 at full reach is hard enough. I would hate to consider another 10' as a first timer with no experience of using a pole at that height..