three barrels empty at a constant rate. The first barrel contains 30 gallons of water. It takes 25 minutes to empty completely. The second barrel contains 40 gallons of water. After 20 minutes, it contains 10 gallons. The third barrel contains the most water. It loses water at a slower rate than both barrels. The third barrel contains X gallons of water and loses water at a rate of X gallon(s) per min