1. **State the problem:** A 1150-gallon tank is full initially and water drains at 26 gallons per minute. 2. **Write the linear equation:** The amount of water decreases over time, so the equation is $$y = 1150 - 26x$$ where $y$ is the amount of water left and $x$ is the time elapsed in minutes. 3. **Explain variables:** - $x$ represents the time elapsed while water drains (minutes). - $y$ represents the amount of water still in the tank (gallons). 4. **Calculate water after 13 minutes:** Substitute $x=13$ into the equation: $$y = 1150 - 26 \times 13$$ $$y = 1150 - 338$$ $$y = 812$$ So, after 13 minutes, there are 812 gallons of water left in the tank.