Respuesta :

Answer:  15

Work Shown:

[tex]n(A \cup B) = n(A) + n(B) - n(A \cap B)\\\\26 = n(A) + 16 - 5\\\\26 = n(A) + 11\\\\n(A) + 11 = 26\\\\n(A) = 26-11\\\\n(A) = 15\\\\[/tex]