Question 253110
Two planes start from the same airport and fly in opposite directions. The second plane starts 1/2 hour after the first plane, but its speed is 80 km per hour faster. Find the groundspeed of each plane if 2 hours after the first plane departs the planes are 3200 km apart.
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Make this chart

                 DISTANCE     RATE     TIME
first plane        
second plane    

Let the rate of the first plane be x
Let the rate of the second plane be 80 kph more or x+80
Fill those in:

                 DISTANCE     RATE     TIME
first plane                    x         
second plane                  x+80      

The first plane's time was 2 hours
The second plane's time was a half hour less or 2-.5 or 1.5 hours 

                 DISTANCE     RATE     TIME
first plane                    x         2
second plane                  x+80      1.5

Use D=RT to fill in the distances


                 DISTANCE     RATE     TIME
first plane         2x         x         2
second plane     1.5(x+80)    x+80      1.5

They are 3200 km apart, so the sum of their distances
equals 3200

                2x + 1.5(x+80) = 3200

Can you solve that? If both post again asking how:

Answer: x=880 

The first plane was traveling 880 kph and the second 
plane was traveling 80kph faster or 960 kph.

Edwin</pre>