Exercise 2: sample answer

The train arrives at 17:00 London time (09:00 plus 8 hours). A city 30 degrees west has solar time behind London's by 30 x 4 minutes = 120 minutes, or two hours. The local solar clock therefore reads 15:00 on arrival.

The traveller's watch, still on London time, reads 17:00, two hours fast compared with the local clock. This is why travellers across large distances needed a system of zones, so that they could reset their watches by a whole number of hours at a known place (the idea behind time zones).