I need help on a math problem

A and B are independent events. Find The missing probability.

P(A) = 3/7, P (A and B)= 1/3. Find P (B

since A & B are independent events,

P(A & B) = P(A).P(B)

P(B) = P(A & B)/P(A) = (1/3) /(3/7) = 7/9 <----------

put them on 21 so

(3x3) / (3x7) = 9 /21 =A

P(A and B)= 7/21

9/21 x P (B) = 7/21

P(B) = (7/21) / (9/21) donc P(B) = 7/9