1. **State the problem:** We need to find the equation of the line of best fit for the scatter plot showing the relationship between the number of books used ($x$) and the time spent on research papers in minutes ($y$). 2. **Analyze the scatter plot:** The points show a positive linear trend roughly from $(6,700)$ to $(16,1400)$. 3. **Calculate the slope ($m$):** $$m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{1400 - 700}{16 - 6} = \frac{700}{10} = 70$$ 4. **Find the y-intercept ($b$):** Using point $(6,700)$ and $m=70$: $$700 = 70 \times 6 + b$$ $$700 = 420 + b$$ $$b = 700 - 420 = 280$$ 5. **Write the equation of the line:** $$y = 70x + 280$$ 6. **Compare with given options:** The closest option is C: $y = 70.28x + 285.21$, which matches our calculation closely. **Final answer:** $$\boxed{y = 70.28x + 285.21}$$