Suppose water contained some harmful volatile substance. how could you easily remove the volatile substance in a laboratory?

Well, you could use a reverse osmosis process to remove all of the fluoride that the United Staes government has put in the water! Every year the Us Gov receives a lot of fluoride from china. Fluoride is a waste and a poison, and instead of the Us Government paying a Buch of money to burn this waste, they just put it in the water! what you need t do, is get your water from the earth. Which is actually the best place to get your water, because its WATER filtered by the earth. Just google wells or springs around your location, some private business/companies offer their water collecting serves, something you should really take advantage of! As for me, I get my water at a place called "Carlsbad alkaline water." good stuff, only 50 cents for 4 gallons. rawr XD  Jesus loves you, and he offers the everything freely, which means you don't need to follow a religion to earn anything. Lets face it, your not perfect, and we need help from God! 

You would do 1500/4 and the answer is 375