Let C denote the set of people who like cricket, T denote the set of people who like tennis.
∴n(C∪T)=65,
n(C)=40
n(C∩T)=10
We know that,
n(C∪T)=n(C)+n(T)–n(C∩T)
∴65=40+n(T)–10
⇒65=30+n(T)
⇒n(T)=65–30=35
Therefore, 35 people like tennis.
Now,
(T–C)∪(T∩C)=T
Also,
(T–C)∩(T∩C)=ϕ
∴n(T)=n(T–C)+n(T∩C)
⇒35=n(T–C)+10
⇒n(T–C)=35–10=25
Thus, 25 people like only tennis.