How do you report hours that vary week to week? after 12 years as a mechanic

My hours change every week at my new part-time job and I am afraid of reporting wrongly. I am in Albuquerque, in case local advice matters. The form asks for gross earnings, which I do not see until later. Who can I ask without risking my claim?

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.