Let $$E$$ and $$F$$ be any two events with $$4 P(E \cup F) = 0.8, P(E) = 0.4$$ and $$P (E/F) = 0.3$$.Then $$(F)$$ is .

A

$$\frac {3} {7} $$

B

$$\frac {4} {7} $$

C

$$\frac {3} {5} $$

D

$$\frac {2} {5} $$