A gas station stands at the intersection of a north-south road and an east-west road.A police car is traveling toward the gas station from the east, chasing a stolen truck which is traveling north away from the gas station.The speed of the police car is 100mph at the moment it is 3 miles from the gas station.At the same time, the truck is 4 miles from the gas station going 80mph.At this moment, is the distance between the car and truck increasing or decreasing?How fast?

(Hint: the 'h' is not constant in this example!! It is changing J)