Why usual speed is subtracted from increased speed why not increased - usual .

Why usual speed is subtracted from increased speed why not increased - usual . 740/0.23:04 Page 8.59 v Q.IO Increased speed of the train = (x + 5) km/hr Time taken by the train under usual 360 speed to cover 360 km = —hr x Time taken by the train under increased 360 hr speed to cover 360km = Therefore, 360 360 {360 (X +5) -360/ Exit