In guinea pigs, the allele for short hair (S) is dominant over the allele for long hair (s), and the allele for white color (W) is dominant over the allele for black color (w). We then cross a guinea pig that is heterozygous for both traits with a tester and they produce the following offspring:

with parental configuration: 45
recombinants: 15

What is the recombination frequency?