Answer:
The number of teachers who teach physics n(P) = 12
Step-by-step explanation:
Step(i):-
Given that the number of teachers who teach mathematics or physics
n(MUP) = 20
Given that the number of teachers who teach mathematics
n(M) = 12
Given that the number of teachers who teach both mathematics and physics
n(M∩P) = 4
Step(ii):-
By using n(A∪B) = n(A) + n(B) - n(A∩B)
n(M∪P) = n(M) +n(P) - n(M∩P)
20 = 12 + n(P) - 4
20 -12 +4 = n(P)
n(P) = 12
Final answer:-
The number of teachers who teach physics n(P) = 12
