Of the 32 students in a certain class, 15 are in a music club and 20 are
in a dance club. If 10 of the students are not in either club, how many of
the students are in only one of the two clubs?
A. 5 B. 9 C.10 D. 17 E. 25
如果设两个社团都都参加为X
15+20-X+10=32, X=13
请问只参加一个社团的人数的算法用两者联集减掉交集
15+20-13=22是哪里出了问题呢?
谢谢