You can put this solution on YOUR website!
For this, a great way to stay un-confused would be to make a diagram.
Draw a little sailboat with a stick figure on it. That's your beautiful Penny. Draw a long stretch of line a little ways away from the boat that reaches farther than the boat. That's your even more beautiful land.
Draw an arrow pointing in the same direction as the front of the boat and write "5 ft/s" next to it. That's how fast your boat is going.
Draw an arrow next to Penny going in the same direction as the other arrow, pointing towards the bow. Write "3 s" after it.
If you look at your drawing--and can tell what's going on--you'll see that you have a rate for how fast your boat is going(5 ft/s) but no rate for how fast your beautiful Penny is going(3 s). You need to find out how fast she's walking, as the problem is asking for a "rate of travel". Don't worry about the "in respect to the land" yet, that will just confuse you more.
You know that Penny is traveling 24 feet in 3 seconds. The question now becomes, how many feet is she traveling per second? You know that you need to find this out because your boat's rate is "5 ft/s", feet per second, and you want to get Penny's rate the same.
To do this, all you've got to do is divide 24 by 3. There are three seconds in which she goes 24 feet, so by doing this you're finding how many feet she travels in one.
Penny is going at 8 ft/s and the boat is going at 5 ft/s.
Since the land isn't moving, and since Penny is moving in the same direction as the boat(see gorgeous diagram), you've just got to add their rates together.
8 ft/s+5 ft/s=13 ft/s
And that's how fast beautiful Penny is moving in relation to the land.
Hope this helps!