Question

if n(a) =20,n(A∩B) =5 then n (a-d)​

Answer 1

Step-by-step explanation:

we have the formula n(A u B)=n(A)+n(B)-n(A ∩ B)

11=7+5-n(A ∩ B)

n(A ∩ B)=7+5–11

n(A ∩ B)=12–11=1

Answer 2

$\huge\underbrace\green{Answer}$

n(A∪B)=n(A)+n(B)−n(A∩B)−−−−−−−(1)

Given n(A)=7

n(B)=9

n(A∪B)=14

Substituting in 1

14=7+9−n(A∩B)

⇒n(A∩B)=16−14=2