Genetics Phenotype Question?

Ian and Bryony are both carriers for two autosomal recessive disorders, PKU (chromosome 12) and cystic fibrosis (chromosome 7). They are expecting a daughter. What is the probability that she will have PKU but not CF? Originally, I thought the answer was 3/16 because thats how many times the daughter has PKU but not CF out of all the possibilities. But the more I think about the question, does it want us to assume that the daughter will inherit PKU for sure, but not CF? In that case, it would be 3/4. I am a bit confused. Thanks.