An ice machine uses 3 gallons of water every 9 hours. how many gallons of water does it use each hour? how many hours does it take to use one gallon? a) 1 9 gallon per hour; 1 hour b) 1 3 gallon per hour; 3 hours c) 3 gallons per hour; 1 9 hour d) 1 3 gallon per hour; 1 3 hour