First we need to calculate how far they both can see.
Pam's eye level height = 324 feet
Using the given formula, we get:

Adam's eye level height = 400 feet
Using the same formula for Adam, we get:

This means, Adam can see 24.49 miles beyond horizon and Pam can see 22.05 mile beyond horizon.
This mean Adam can see 24.49 - 22.05 = 2.44 miles father to the Horizon than Pam.