Answer:
Caleb arrived earlier.
Also, he arrived 2 hours earlier.
Explanation:
We know that,

For Alyssa,
Distance = 105 miles,
Time = 3.5 hours,
∴ Alyssa's speed =
= 30 miles per hour,
For Caleb,
Distance = 168 miles,
Time = 4 hours,
∴ Caleb's speed =
= 42 miles per hour,
Since, they are driving with the constant speed,
Thus, Caleb's speed > Alyssa's speed
That is, Caleb will arrive earlier, ( Time ∝ 1 / speed )
Now, they both have to cover 210 miles,
Time taken by Caleb in the entire journey =
= 5 hours,
While, the time taken by Alyssa in the entire journey =
= 7 hours,
∵ 7 - 2 = 5
Hence, Caleb arrived 2 hours earlier.