Not a difficult problem but a little bit tricky

Considering that the numbers are in percentages and weird, especially the 9%. Difficult to pik a number to have a net number. However, the answer choices are far apart so we can also work by estimation

TS= total students

These can be divided into two categories : T with tubercolosis and those without NO tubercolosis

Those with T can be divided further into those \(\geq 20\) and those < 20 years

Now, in those kind of question usually is best to look at the phrase we do have in the end, to have the overall total of people involved. In this case

If 9% of the total students are more than or equal to 20 years of age and are susceptible to tuberculosis

So we do have T and \(\geq 20\) are 9%

This means that the other three categories involved T and <20, NT and \(\geq 20\), NT and <20 are 91%

Then we have that the category T and <20 is 10%

Therefore the two categories NT and \(\geq 20\) , NT and <20 are 81%

Of this last categories NT and \(\geq 20\) is 40% = 38.4 and NT and <20 is 48.6

The question is

what percentage of the students, that are 20 years old or more, are not susceptible to tuberculosis?

means \(\frac{38.4}{48.6}=66.6\)

The other answer choices are inferior to this value. So the answer must be E