SOLUTION: Two planes start from the same airport and fly in opposite directions. The second plane starts 0.5 hours after the first plane, but it's speed is 80 km/hr faster. Find the speed of

Is that 2 hours after the first plane left, or 2 hours after the second 
plane left?  You didn't tell us, and "after 2 hours" doesn't tell us,
So I'll have to do it both ways, and you'll have to ask your teacher 
whether the 2 hours was after the first plane left or 2 hours after the 
second plane left.

If it was 2 hours after the first plane left then the first plane 
flew for 2 hours and the second plane flew for 1.5 hours.

If it was 2 hours after the second plane left then the first plane 
flew for 2.5 hours and the second plane flew for 2 hours.

1.  Assuming it was 2 hours after the first plane left.

Make this chart: 
                        Distance     Rate     Time 
First plane to leave                                     
Plane that left later   


Fill in those two times:

                        Distance     Rate     Time 
First plane to leave                            2
Plane that left later                          1.5

Let x = the rate of the first plane to leave, and since the
second plane to leave was flying 80 km/hr faster, its rate
is x+ 80.  So we fill those in: 

                        Distance     Rate     Time 
First plane to leave                  x         2
Plane that left later                x+80      1.5


Now we fill in the Distances using Distance = Rate × Time

                        Distance     Rate     Time 
First plane to leave       2x         x         2
Plane that left later   1.5(x+80)    x+80      1.5


The sum of the distances must equal 3200 km

               2x + 1.5(x+80) = 3200
              2x + 1.5x + 120 = 3200
                   3.5x + 120 = 3200
                         3.5x = 3080
                            x = 
                            x = 880 km/hr

If the 2 hours is after the second plane left then

The first plane to leave traveled 880 kn/hr and the
second one to leave traveled 80 km/hr faster or 960 km/hr 

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2.  Assuming it was 2 hours after the second plane left, the
times are different

                        Distance     Rate     Time 
First plane to leave      2.5x         x       2.5
Plane that left later    2(x+80)     x+80       2


The sum of the distances must equal 3200 km

               2.5x + 2(x+80) = 3200
              2.5x + 2x + 160 = 3200
                   4.5x + 160 = 3200
                         4.5x = 3040
                            x = 
                            x = 
                            x = 675.6 approximately
                            
The first plane to leave traveled approximately 675.6 kn/hr and the
second one to leave traveled 80 km/hr faster or 755.6 km/hr approximately.

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The first way came out an exact answer.  This one came out a fraction.
But either is feasible.  Take your pick or ask your teacher which one
is the right one.

Edwin