Toby's bucket has a leak. The bucket starts with 5 gallons of water. After 7.5 minutes, there are only 2.5 gallons in the bucket of water. The equation is 5 + 7.5r=2.5 represents this situation, where r is the rate of change of water in the bucket. Suppose you use arithmetic to find the rate of change. How can the equation help guide your steps? What are the steps and what does the result of each step represent?