Given data:
The number of students who play a sport and instrument are a=23.
The number of students who play a sport but not instrument are b=15.
The number of students who don't play sport but play instrument are c=18.
The number of students who don't play sport and instrument are d=4.
The expression for the total numbers of students are,
n=a+b+c+d
Substitute the given values in the above expression.
n=23+15+18+4
n=60
The expression for the students who donot play an instruments are,
x=b+d
Substitute the given values in the above expression.
x=15+4
=19
Thus, the total numbers of students are 60, and the students who donot play an instruments are 19.
