Number of chromatids in G₁ and G₂ respectively in a somatic cell with 2n = 20 are

Here 2n = 20 means there are 2 genomes (haploid set of chromosome is called genome). Each chromosome has two chromatids as they are attached to centromere. Thus in a somatic cells with 2n =20, the number of chromatids in G₁ and G₂ is 20 and 40 respectively.