<PRE><B>Question 516091</B>
plane I speed = x  km/h
Plane II speed= x+100

add up speeds 
=2x+100

plane I has traveled 0.5x miles before plane II starts

So the distance when plane II starts = (3300-0.5x)

combined speed = 2x+100

time = 3/2 hours  (Plane II starts 1/2 hour later. 2-0.5 = 1.5 hours )

3/2 = (3300-0.5x)/(2x+100)

3(2x+100)=2(3300-0.5x)

6x+300=6600-x

7x=6300
x=6300/7
x=900 km/h  plane I

Plane II = 1000 km/h
CHECK

plane I distance + plane II distance = 3300

900*2+1000*1.5=3300 km

m.ananth@hotmail.ca

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