# 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.