The rule for conditional probability states that
[tex] P(A|B) = \dfrac{P(A\cap B)}{P(B)} [/tex]
Since we're given both numerator and denominator, we only need to plug the values in:
[tex] P(A|B) = \dfrac{\frac{4}{7}}{\frac{7}{8}} = \dfrac{4}{7}\cdot \dfrac{8}{7} = \dfrac{32}{49} [/tex]
