Answer:
U.S. : 10,000 tickets
Korea: 10,000 tickets
Step-by-step explanation:
1. Set 15x + 20y = 350,000 and x + y = 20,000
2. x + y = 20,000 ---> y = 20,000 - x
3. Plug in y into the 20y ---> 15x + 20(20,000 - x) = 350,000
4. 15x + 400,000 -20x = 350,000
5. -5x = -50,000
6. x = 10,000
7. Plus in x in y = 20,000 -x ---> y = 20,000 - 10,000
8. y = 10,000