Question

With a uniform speed a car cover a certain distance in 8 hours. Had the speed been increased by 4 km/hr, the same distance could have been covered in 7 1/2 hours. What is the distance covered?

Answer 1

distance=speed× time
according to the 1 condition
d=s×8
therefore, speed = d/8.................(1)
according to the 2 condition
d=(s+4)×15/2............(2)
from 1 and 2
d=(d/8+4)×15/2
d=(d+32/8)×15/2
d=15d+480/16
16d=15d+480
16d-15d=480
d=480
therefore distance travel is 480