Question

a train leaves from new york to chicago at 60mph. ANother train leaves from Chicago to New York at 40 mph. How far apary are the train one hour before they pass each other?

Answer 1

100 miles

Explanation:

Relative Speed: 60+40=100 mph

you can think that one train is stationary,another one is 100 mph

so one hour before the train pass each other，the distance is 100 miles