A dog walking along some train tracks meets a train every 4 minutes and the train catches up the dog every 12 minutes. Find the value of x if the trains leave the endpoint of the route every x minutes.

Answer and Step-by-step explanation:

Dog meets the train in = 4 minutes

Train catches up the dog in = 12 minutes

Let x be the time when train leave the route,

Train catch up the dog in 12 minutes, the endpoint of route is x and the dog meet up the train in 4min, so the equation becomes:

                       12 - x = 4

               To find out the value of x, subtract 12 from both sides, we get

                        x = 4 – 12

                         -x = -8

Which gives x = 8, when train leaves the endpoint of route.