Math problem 54 students, 22 can play volleyball, 27 can play basketball, 12 can't play both kinds of balls, how many people can play both kinds of balls?
Let the person who can only play volleyball be X, the person who can only play basketball be Y, and both of them are Z.
X+Y+Z+ 12=54
X+Z=22
y+Z=27
X= 15 Y=20 Z=7。
A: There are seven people who can answer both kinds of balls.
This is the method of junior high school, and it should be simpler to use the method of assembly, but I don't know what grade you are in, so that's it.