How do you report hours that vary week to week? (Portland)

I work some days through a staffing agency while still certifying. Any experience at all would help. The form asks for gross earnings, which I do not see until later. Did anyone get an overpayment notice from a mistake?

In my state the question was about the week I worked, not the week I was paid. Read the wording on your form carefully, or ask the claims line.