Is the question
If so the give tells you that (complement).
At the start of flue season, Dr. Anna Ahmeed examines 50 patients over two days. Of those 50 patients, 30 have a headache, 24 have a cold, and 12 have neither symptoms. Some patients have both symptoms.
Draw a Venn diagram and determine the number of patients that have both symptoms.
How do I figure out how many have both?
The answer is this (8a):