Question

Ina a school there are 20 teachers who teach mathematics or physicscof these 12 teach mathematics and 12 teach physics how many teach both the subjets

Answer 1

Answer:

Out of these teachers the number of teachers who teach mathematics only is 12. So, we can write n(P) = 12. Also, we come to know that there are 4 teachers who teach physics and mathematics both. Thus we have that n(P ∩ Q) = 4.