Answer
Please see the work below.
Work Step by Step
We know that there are four different possibilities for each base in the codon, hence $4\times 4\times 4=64$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.