How many applicants DID NOT have advanced expertise in any of the three given fields?

Here, we need to represent all the given data in a three sets venn-diagram that is Data Analytics (A), Database Handling (H), and Coding (C).

If we write all the data that is given in the table, we will get the following diagram:

Now we need to infer the characteristics of x, which can be concluded from the given information.

We know that $$2-x\ge\ 0$$, hence the possible values of x is 0, 1, 2

It is also known that $$x-2\ge\ 0$$, which implies the possible values of x is 2, 3, 4, ....

Now, from both equation, the only common value of x is 2.

Hence, x can take only 2 as the value.

Now the total number of people who know atleast one of the three is (x+4)+(2-x)+x+x+(6-x)+(3-x)+(x-2)=x+13=2+13=15.

 We know the total is 41 members. So, the number of people who don't know atleast 1 is 41-15=26.