What should i have for breakfast?

What is the order of magnitude for the number of liters in a large bottle of soda served at a party

Atrain leaves little? rock, arkansas, and travels north at 90 kilometers per hour. another train leaves at the same time and travels south at 80 kilometers per hour. how long will it take before they are 680 kilometers? apart?

What’s the answer? and how do i solve it ?