Question 687419
John and Jack walk towards each other at the same time from two places that are 100km apart.
 John walks at 6km/h and Jack 4kn/h.
 John has a dog that runs at 10km/h and starts together with him.
 The dog turns back each time when it meets Jack or John.
 How long has the dog run when these two guys meet each other?
:
Let t = time John and Jack walked when they meet
:
Write distance equation, dist = speed * time
:
John's dist + Jack's dist = 100 km
6t + 4t = 100
10t = 100'
t = 100/10
t = 10 hrs
:
The dog ran for 10 hrs, his speed is 10 km/hr, therefore
10 * 10 = 100 km was the dist ran by the dog