Having traveled half the way in an hour, the driver reduced the speed of the electric train by 40 km / h

Having traveled half the way in an hour, the driver reduced the speed of the electric train by 40 km / h and therefore covered the second half of the journey in 1 hour and 15 minutes. At what speed did the electric train travel the second half of the journey?

Suppose that the electric train passed the first half of the journey at a speed of x km / h.
According to the condition of the problem, the electric train then reduced its speed by 40 km / h, which means it continued to move at a speed of x – 40 km / h.
Since 15 minutes is equal to 1/4 hour or 0.25 hours, then 1 hour 15 minutes = 1.25 hours.
Thus, the first half of the track of the electric train is x * 1 = x km, and the second half of the track is 1.25 * (x – 40) km.
Let’s make the equation:
x = 1.25 * (x – 40),
x = 1.25 * x – 50,
1.25 * x – x = 50,
0.25 * x = 50,
x = 200 km / h.
This means that, having reduced the speed by 40 km / h, the train was traveling at a speed
200 – 40 = 160 km / h.