Answer:
The number of students that like only Nokia
Step-by-step explanation:
consider N the number of students who like Nokia → N=?
T the number of students who like Techno → T=35
Statement 1: In a class of 40 students, 5 like neither Nokia nor Techno
we can translate it like this: 35 student like Nokia or Techno
we can note it like this : T∪N= 35
Statement 2: 30 like Techno and Nokia
we can note it : T∩N = 30
using a rule concerning the number of element of a set :
T∪N = N + T - T∩N
then
35 = N + 35 - 30
⇒ N - 30 = 0
⇒ N = 30
