How many are not taking a course in either computer science or in mathematics? Suppose that there are 1807 students at university. Of these, 453...

the correct ans is

You have
enough to find n(M U C) = n(M) + n(C) - n(M ∩ C). Those are the total of students who
are taking either computer science or mathematics.
The remainder, 1807 minus
that number, is the number who are taking neither.
You could work out those
other counts too. 453 are taking computer science. 299 of those are also taking
mathematics. So 453 - 299 are taking only computer science.
567 are taking
mathematics. 299 of those are also taking computer science. So 567-299 are taking only
mathematics.
Now you have the disjoint sets (math only), (computer science
only) and (both math and computer science), and you could subtract those from 1807 to
get (neither)