Answer:
of Steph's annual income is from her full-time job.
Explanation:
Suppose, Steph's annual income is

Given that, 80% of Steph's annual income is from her full-time job.
So, the amount of income from her full time job will be:

Now, for finding the income from her full time job as a fraction of Steph's annual income, we just need to divide "income from full time job" by "total annual income".
So, the fraction will be:

That means,
of Steph's annual income is from her full-time job.