To find out how many pages Stephen reads each week compared to Alice, we first need to calculate the average number of pages Stephen reads per week.
Stephen reads a total of 278 pages in 7 weeks:
\[ \text{Pages per week (Stephen)} = \frac{278 \text{ pages}}{7 \text{ weeks}} \approx 39.71 \text{ pages/week} \]
Alice reads 31 pages each week.
Now, we can find the difference between the pages Stephen and Alice read each week:
\[ \text{Difference} = \text{Pages per week (Stephen)} - \text{Pages per week (Alice)} \approx 39.71 - 31 = 8.71 \text{ pages} \]
So, Stephen reads approximately 9 more pages per week than Alice. Since the options provided are 20, 70, 0, and 10, the closest answer is 10.