Having freckles is dominant (F) and not having freckles is recessive (f), A mother has Ff and a father has Ff , if they have a child which genotype will make the child have freckles

For the child to have freckles his genotype must be FF of Ff

Explanation:

Since freckles is dominant (F) and not having freckles is recessive (f), If the child has a genotype with at least one dominant gene (that is FF, Fr) , the child would have freckles but for the child not to have freckles, the genotype gene must both be recessive (that is ff)

Since the other has Ff and a father has Ff, if they have four children, the children genotypes would be FF, Ff, Ff and ff. Since freckles (F) is dominant for the child to have freckles his genotype must be FF of Ff