How long is 420 kilometers in hours?

Answer 1

It's not possible to convert directly between distance and time. If that were possible,
then you'd be able to calculate how many minutes wide your kitchen is, and how many
yards of sleep you had last night.

Are you asking how long it takes to travel 420 kilometres ? That of course depends
on how you travel, especially how fast. The answers for walking, cycling, driving, and
flying are all different. You haven't given that information in the question, leaving me
no way to approach an answer.