Solution:

Let’s say A, B and C are the set of people who like product A, product B and product C respectively.

So now, as per the question,

n (A) = 21 be Number of students who like product A,

n (B) = 26 be Number of students who like product B,

n (C) = 29 be Number of students who like product C,

be Number of students who like both products A and B,

be Number of students who like both products A and C,

and be Number of students who like both product

be Number of students who like all three product,

Now from the Venn diagram, we have,

be Number of students who only like product

students