Fluoridation is done by continuously adding sodium fluoride to water drawn from a reservoir. Assume you are responsible for the fluoridation of your city's water. How many tons of sodium fluoride must you add to the water supply each year (365 days) to maintain a fluoride ion concentration of one part per million (one ton of F- ion per million tons of water)? You live in a city with 150,000 people and each person uses 175 gallons of water per day.

Also given:

1 gallon of water has a mass of 8.34 pounds.

1 pound = 453.6 grams.

1 ton = 2000 pounds.

Sodium fluoride is 45.0% fluoride by mass.

According to the back of my textbook, the answer is 89 tons per year. But I can't figure out how to get that answer.

If anyone could help me by showing me how to work out the problem I would really appreciate it. Thanks!