Conceptual question: how can we extract specific values that fall under multiple conditions using SQL?

I am trying to understand how to derive a percentage of values that specifically fall within multiple categories from more than two tables. For example, given a sample scenario where only a small number of adults who caught the flu died. How do you find a percentage of adults with flu that died and a percentage of adults with flu that didn't die?

There are a total of three tables pasted below for your reference. The first table has a list of people that indicate general information about the person, such as name, age, income, etc. The second table has a list of people that indicate a variety of people's illnesses, such as being sick from the flu. The last table indicates a list of people who have died and their cause of death.

How can one derive the desired output using SQL? One can also use a combination of R functions (such as merge function) as the SQL code would be run in an R environment.

Sample Table 1

Name   Age   Gender
Andrew 25    Male
Lisa   21    Female
Conor  35    Male
John   51    Male
Linda  29    Female

Sample Table 2

Name    Illness
Andrew  Flu
Conor   Flu
Lisa    Flu
John    Smallpox

Sample Table 3

Name    Cause of Death
Andrew  Flu

Desired Output

Fatality(Death from Flu)   Percentage of people with flu
Yes                        1/3
No                         2/3