Question

A man travelled a distance of 60 km in 7 hours. he travelled partly on foot @ 6 km/hr and partly on bicycle @ 12 km/hr. what is the distance (in kms) travelled on foot?

Answer 1

let dist travelled by foot = x km
then , dist travelled by bicycle = 60 - x km
time = dist / speed

speed on foot = 6 km/h
speed on bicycle = 12 km/h

time taken on foot = x/6 hr
time taken on bicycle = 60-x/12 hr
total time taken = 7 hr
total time = time on foot + time on bicycle

7 = x/6 + (60-x)/12
7 = (2x + 60-x)/12
7 = (60 + x)/12
7*12 = 60 + x
84 = 60 + x
x = 84-60 = 14 km ...

Answer 2

Let the distance covered on

foot be 'x' km.

So,

  The distance covered by bicycle

  would be 60 - x km.

                                                   

Time taken for the distance

covered on foot = x/6 h

                                                 

Time taken for the distance

covered by the bicycle = $\dfrac{60-x}{12}\:km$

                                                 

Now, the total time taken

is 7 hours.

                                                   

According to the question

$\dfrac{x}{6}+\dfrac{60-x}{12}=7\\\\\\\implies12x+6(60-x)=7\times72\\\\\\\implies12x+360-6x=504\\\\\\\implies6x=504-360\\\\\\\implies6x=144\\\\\\\implies x=\dfrac{114}{6}\\\\\\\implies x=19$

                                                 

Hence the man traveled 19 km

on foot.