Take into account that the probability for two independent events P(A) and P(B) is given by:
P(A|B) = P(A)P(B)
That is, the probability that both A and B events occur is the product of its probabilities as independent events.
Then, based on the information of the question, you have:
P(A|B) = (3/4)(3/8) = 9/32
The probability is 9/32