Calculating revenue from roller coaster rides
One of the suggestions I would make is to improve your input handling. You don't handle invalid integers well at all.

string input = "invalid int";
int numAvailablePlaces = 0;

while (!int.TryParse(input, out numAvailablePlaces))
{
    Console.WriteLine("Please enter a valid integer for the number of places available.");
    input = Console.ReadLine();
}


And similarly for the other int's you grab. (You could also do them all in one loop.)



This method:


private static int CountDirhamsEarnedInOneOperation(int numAvailablePlaces, LinkedList&lt;int&gt; numPeopleInEachGroup)
{
    //Each passenger pays one dirham to take the ride once.
    int dirhamsEarned = 0;
    int numGroupsInQueue = numPeopleInEachGroup.Count();

    while (numPeopleInEachGroup.First() &lt;= numAvailablePlaces &amp;&amp; numGroupsInQueue &gt; 0)
    {
        dirhamsEarned += numPeopleInEachGroup.First();
        numAvailablePlaces -= numPeopleInEachGroup.First();
        numPeopleInEachGroup.AddLast(numPeopleInEachGroup.First()); 
        numPeopleInEachGroup.RemoveFirst();
        numGroupsInQueue--;
    }

    return dirhamsEarned;
}



Does too much. Break the inside of that while loop to a new method.



Other than that, there's little to say in my opinion.