Answer: 175,000 dollars
====================================================
Work Shown:
2/3 of 15,000 = (2/3)*15000 = 10,000
This means 10,000 people take the shuttle bus to the park. If each person pays $5 to take the bus, then the city earns 5*10,000 = 50,000 dollar through this option.
The rest pay for parking, so 15,000-10,000 = 5,000 people pay for parking. At $25 each, this amounts to 25*5,000 = 125,000 dollars earned through this option.
Overall, the city earns a total of 50,000+125,000 = 175,000 dollars
Side note: this assumes that the remaining 5,000 people all take separate cars and no single car has more than one person. This is very unrealistic as there are likely to be families or carpools of some kind. So in reality, the answer shown above is an upper estimate of the total revenue.