(a)
The Venn diagram helps to solve this type of problem. Here's the key:
A=Commerce students who didn't take any of the 3 subjects.
B=Ins only students
C=Math only
D=Eng only
E=Ins+Eng only
F=Math+Eng only
G=Ins+Math only
H=All 3
Now some figures:
A+B+C+D+E+F+G+H=120
B+E+G+H=38
D+E+F+H=36
C+F+G+H=100
E+H=26
F+H=22
G+H=26
H=18
So, E=8, F=4, G=8.
C=100-(4+8+18)=70
D=36-(8+4+18)=6
B=38-(8+8+18)=4
A=120-(4+70+6+8+4+8+18)=2
(a) A=2 students took none of the 3
(b) C=70 students took math only
(c) E=8 students took ins and eng only
(d) B+C+D=80 students took only one course
(e) E+F+G=20 students took only two courses