SOLUTION: Two planes took off from an airport at the same time and flew in opposite directions. One plane traveled 120 miles per hour faster than the other. At the end of three hours the pl

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Question 426472: Two planes took off from an airport at the same time and flew in opposite directions. One plane traveled 120 miles per hour faster than the other. At the end of three hours the planes were 1500 miles apart What was the average speed of the slower plane?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Plane A x mph
Plane B x+120 mph
..
They are going away from each other.
So add up their speed.

combined speed = x+x+120
=2x+120
Time = 3 hours
Distance = 1500 miles
Distance = speed * time
(2x+120 )*3=1500
6x+360= 1500
6x=1500 -360
6x=1140
/6
x=190 mph Plane A
Plane B 190+120 =310mph