1) A gas station sits 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 100 mph 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 80 mph. What is the rate of change of

the straight line distance between the two vehicles at this moment?