Answer: Hence, Troy spend 9.09 in U.S. dollars.
Explanation:
Since the foreign exchange rate between the U.S. dollar and the Swiss franc is 1:2.2.
It means,
1 U.S. dollar = 2.2 Swiss Franc
Now, According to question, Troy spent 20 Swiss francs to stay one night in a youth hostel.
So, 1 Swis Franc =

20 Swiss Franc =

Hence, Troy spend 9.09 in U.S. dollars.