If the vehicle speed is increased by 20%, it will be 1+20%= 1.2, and the time will be changed to11.2 = 5/6.

So the original time is 1/( 1-5/6)=6 hours.

Similarly, the time taken to speed up by 25% is 4/5 of the original time of this section, and the time saved is 1-4/5= 1/5 of the original time of this section.

The original time of this section: 40/( 1/5)=200 minutes.

Original speed line120km: 360min-200min =160min.

Distance: 360 * (120/160) = 270km.