De Morgan's Laws

Q. If A, B and C are any three sets, then $A-(B\cup C)$ is equal to

1. $(A-B)\cup (A-C)$
2. $(A-B)\cap (A-C)$
3. $(A-B)\cup C$
4. $(A-B)\cap C$

Q. Let $n\left(U\right)=700,n\left(A\right)=200,n\left(B\right)=300$ and $n(A\cap B)=100$, then $n(A^c\cap B^c)$ equals to

1. $400$
2. $600$
3. $300$
4. $20$

Q. There are $80$ families in a small town extension area. $20\%$ of these families own a car each. $50\%$ of the remaining families own a motor cycle each. Let $N$ families in that extension do not own any vehicle. Then the value of $\frac{N}{4}$ is

Q. In an examination, out of $100$ students, $75$ passed in English, $60$ passed in Mathematics and $45$ passed in both English and Mathematics. The number of students who passed in none of the two subjects, is
(Assume all students gave both the exams)

1. $5$
2. $10$
3. $20$
4. $40$

Q.

${\left[\right(A^{\prime }\cup B^{\prime })-A]}^{\prime }$=___

1. A

2. B

3. B - A

4. A - B