<PRE><B>Question 328338</B>


let speed of south bound plane be x
north bound plane = x+100  (  presume it is 100 more)
Time thay travel = 5 hours
distance of south boundplane = 5x
distance of north boundplane = 5(x+100)
..
5x+5(x+100)=2000
5x+5x+500=2000
10x+500=2000
10x=2000-500
10x= 1500
x= 150 mph south bound plane
..
north bound plane  speed = x+100 = 150+100=250 mph

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CHECK
150*5+250*5= 2000</PRE>