In a DNA molecule, three nucleotides make up a codon. A codon is creates a specific amino acid. Therefore, in order to work this out, we must calculate the number of codons that will not be affected by the mutation. This is done by finding the highest number that is divisible by 3 but less than 85. This can be done by:
85 / 3 = 28.333
So 28 codons will not be affected.
