ANSWER
P(A and B) = 1/2
EXPLANATION
By the Bayes Theorem we have a relationship between the given probabilities:
[tex]P(A\text{ and B)}=P(B)\cdot P(A|B)[/tex]In this problem P(B) = 4/7 and P(A|B) = 7/8:
[tex]P(A\text{ and B)}=\frac{4}{7}\times\frac{7}{8}=\frac{4}{8}=\frac{1}{2}[/tex]