posted by Jake .
A plane leaves Boston at 10 am (Boston time) and flies non-stop to LA, 2700 miles away, at 580 miles per hour (mph). On the same route, a second plane is flying non-stop from LA to Boston at 620 mph. If the second plane lease LA at 10 am (LA time), how many miles from LA will the second plane be when the two planes meet?
the two planes cover 580+620=1200 miles per hour.
So, they travel for 2700/1200 = 2.25 hrs before meeting. (why?)
In that time, the 2nd plane has traveled 2.25*620 = 1395 miles, so it is 1305 miles from LA.