Question

A man covers a distance of 15 km in 3 hours ,partly by Walking and partly by running. If he walks at 3km/hr and runs at 9 km/hr then the distance covered by running is

Answer 1

let the time at walking be x

so time during riding =3-x

now from question

3x+9(3-x)=15

3x+27-9x=15

-6x=-12

6x=12

x=12/6=2

so time at walking =2hour

and time at riding=3-2=1hour

Answer 2

Let hours of walking be y hours and running be x hours

According

9x - 3y = 15

9x - 3y = 3

y = 2 hours

substitute value of y

9x + 3y = 15

9x = 9

x = 1 hours

Distance covered = speed × time

= 9 km/h × 1 hour

= 9 km.

He covered 9 km by running.