If a car moves an average speed of 51 km/hr for an hour, it will travel a distance of 51 km. how far will it travel if it continues this average rate for 8 hrs

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?