# At 11 o’clock, two planes took off from the airfield simultaneously in opposite directions.

At 11 o’clock, two planes took off from the airfield simultaneously in opposite directions. One of them flew at a speed of 3540 km. One of them flew at a speed of 620 km per hour. How fast was the second plane flying?

The condition is not given in full. The distance between the planes is 3540 km at 14.00. We solve the problem in two ways.
Option 1.
Finding time in flight:
14 – 11 = 3 (hours).
We find the distance covered by the first plane:
620 * 3 = 1860 (km).
Find the distance of the second plane:
3540 – 1860 = 1680 (km).
Find the speed of the second:
1680/3 = 560 (km / h).
Option 2.
Find the time of movement:
14 – 11 = 3 (hours).
Finding the speed of removing planes:
3540/3 = 1180 (km / h).
Finding the speed of the second plane, knowing the speed of the first:
1180 – 620 = 560 (km / h).
Answer: the speed of the second is 560 km / h.

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