Let A be the set of people who read newspaper H.
Let B be the set of people who read newspaper T.
Let C be the set of people who read newspaper I.
Given n(A) = 25, n(B) = 26, and n(C) = 26
n(A∩C) = 9, n(A∩B) = 11, and (B∩C) = 8
n(A∩B∩C) = 3
Let U be the set of people who took part in the survey.
n(A∪B∪C) = n(A) + n(B) + n(C) − n(A∩B) − n(B∩C) − n(C∩A) + n(A∩B∩C)
= 25 + 26 + 26 − 11 − 8 − 9 + 3
= 52
Hence, 52 people read at least one of the newspaper.