120 students were asked about skiing. Here are the results of the poll:
1. Have you skied either cross-country or downhill? Yes: 65 No: 55
2. If you answered Yes to Question 1, did you ski downhill? Yes: 28 No: 37
3. If you answered Yes to Question 1, did you ski country-country? Yes: 45 No: 20
How many students skiied both cross-country and downhill?
I'm not sure why it is 8?