1. **State the problem:** We are given a scatter plot showing the relationship between average monthly temperature $x$ (in °F) and monthly heating cost $y$ (in dollars) for 23 months. We need to find an approximate equation of the line of best fit and then use it to predict the heating cost at $x=45$ °F. 2. **Analyze the scatter plot:** The plot shows a negative linear trend, meaning as temperature increases, heating cost decreases. 3. **Estimate the line of best fit:** From the description, points range roughly from $(10,90)$ to $(80,10)$. 4. **Calculate slope $m$:** $$m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{10 - 90}{80 - 10} = \frac{-80}{70} = -1.14$$ 5. **Calculate intercept $b$:** Using point $(10,90)$, $$90 = -1.14 \times 10 + b \implies b = 90 + 11.4 = 101.4$$ 6. **Write the equation:** $$y = -1.14x + 101.4$$ 7. **Predict heating cost at $x=45$:** $$y = -1.14 \times 45 + 101.4 = -51.3 + 101.4 = 50.1$$ **Final answers:** (a) $y = -1.14x + 101.4$ (b) Predicted heating cost at 45 °F is $50.10$ dollars.