It is really difficult to interpret what you have posted.

I take it that A is the set of multiples of 15 from 1 to .

B is the set of multiples of 33 from 1 to .

The question want to know how elements are in the set .

That is the number of integers from 1 to which are multiples of 15and notmultiples of 33.

That is .

If that is not what you mean, then what do you mean?