Answer:
17
Step-by-step explanation:
n(Band and Choir only)
= 25 - 11 - 7 - 3 = 4
n(Math and Band only)
= 7
n(Math and Choir only)
= 57 - (25 + 17 + 9)
= 6
Exactly 2:
4 + 7 + 6
= 17
