Question

A man cover a certain distance by his car,if he travels 6km/hr faster he takes 4hr less time, but if he drive 6km/hr slower then he takes 6hrs more.find the distance

Answer 1

Let t be the usual time taken by the man to cover the distance
Let d be the distance, s be the usual speed

Usual time taken => d/s = t => d=ts
d/(s+6) = t-4
ts/(s+6) = t-4
ts = ts+6t-4s-24 
6t - 4s - 24 = 0 --> (1)

d/(s-6) = t+6
ts = ts-6t+6s-36
-6t + 6s - 36=0 --->(2)

Solving (1) nd (2), v get

s = 30 km/h
t = 24 hrs
d = t * s
d = 30 * 24 = 720 km

Ans : 720 km