To determine the inequality that Paolo solved, we need to interpret the information provided about the number line.
The number line has an open point at 4, and there is a leftward arrow from that point, indicating that the solution includes all values less than 4. Therefore, the solution to the inequality would be x < 4.
Now, we can analyze the given options:
- \(3.7x > 14.8\) implies \(x > \frac{14.8}{3.7} \approx 4\) (not the correct direction).
- \(2.8x < 10.5\) implies \(x < \frac{10.5}{2.8} \approx 3.75\) (this is less than 4).
- \(4.9x > 19.6\) implies \(x > \frac{19.6}{4.9} = 4\) (not the correct direction).
- \(2.1x < 8.4\) implies \(x < \frac{8.4}{2.1} = 4\) (this is also less than 4).
Since the solution must be values less than 4, both the second option \(2.8x < 10.5\) and the fourth option \(2.1x < 8.4\) are valid inequalities based on the information provided about the number line.
However, since the number line depicts values less than 4 and does not include 4, Paolo must have solved an inequality representing all numbers less than a value (not including that value), so the best fit would be the one with a solution that does not include the number 4.
Both options (2) and (4) satisfy \(x < 4\), but \(2.8x < 10.5\) gives a more restrictive condition as it gives a value less than 4.
Thus, the correct answer is:
2.8x < 10.5