Question

two cities are 2160 miles apart. a plane leaves one of them, traveling towards the other at an average speed of 320 miles per hour. at the same time a plane leaves the other, traveling towards the first, at an average speed of 400 miles per hour. How long will it take them to meet?

Answer 1

Speed=distance /time ⇒ distance=Speed x time.
A=a city
B=other city.


320 miles/h 400 miles/h
----------------→ ←----------------

A-----------------------------------------------------------B
2160 miles

x=time

We can sugget this equation:
320x+400x=2160
720 x=2160
x=2160/720
x=3

Answer: 3 hours.