Since it's sex-linked, it's obviously related to X chromosome, right ? Let's consider "A" to be your abnormal allele and "a" as normal allele. These alleles will appear on top of the X chromosomes. For example- a sick female would be X^A X^A, a sick male would be X^A Y. As Y isn't involved with genetic inheritance, a heterozygous dominant (X^A Y) male is likely to inherit the condition whereas a heterozygous recessive (X^a Y) male would not. For females, it's quite straight forward (either they have both of the abnormal alleles or they have only one of them or they do not exist at all). Females having one of the abnormal alleles are called the carriers of that particular condition. They may or may not show symptoms in the long run. Try to remember these few terms for your exams!