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

I picked up part-time shifts as a graphic designer and I am confused about how to report them. I have been trying to stay organised about it. The form asks for gross earnings, which I do not see until later.

The claimant handbook has worked examples for part-time pay. Mine was clearer than the phone line.

I estimated and then checked my pay stub. When there was a small difference I wrote to the agency to correct it.