Answer:
6 students
Step-by-step explanation:
Total number of students = 59
Number of poetry = 22
Number of history = 27
Number of writing = 28
Number who signed for exactly 2 = 6
Number who singed up for all 3 = x
Using the knowledge of Venn diagram:
n(Total) = n(Poetry) + n(History) + n(Writing) - n(Exactly 2) - 2x
59 = 22 + 27 + 28 - 6 - 2x
59 = 77 - 6 - 2x
59 = 71 - 2x
59 - 71 = - 2x
-12 = - 2x
x = 6