If A and B are two independent events such that $P(B)=\large\frac{2}{7}$$,P(A \cup B)=0.8,$ then $P(A)$ is equal to :

Question

\[\begin {array} {1 1} (a)\;0.1 & \quad (b)\;0.2\\ (c)\;0.3 & \quad (d)\;0.4 \end {array}\]