Let the uniform speed of the car be x km/hr. Distance covered by the car in 8 hours =8xkm Increased speed of the car=(x+4)km/hr Distance covered by the car in 7 hours 30 minutes,i.e.,
15
2
hours =
15
2
(x+4)km ∴8x=
15
2
(x+4) 16x−15x=60 ⇒x=60 Distance covered by the car =8×60=480km