Question

Use the union rule to answer the question.If n(A n B) = 7, n(A U B) = 54 and n(A) = 35, what is n(B)?n(B) =(Simplify your answer.)

Answer 1

n(A U B) = n(A) + n(B) - n(A n B)

From the question;

n(A n B) = 7 n(A U B) = 54 n(A) = 35

substituting the values into the formular above and then solve for n(B)

54 = 35 + n(B) - 7

54 = 28 + n(B)

subtract 28 from both-side of the equation

54 - 28 = 28 - 28 + n(B)

26 = n(B)