There is no dollar amount on my speeding ticket do I have to pay something?

I got a ticket in Troutdale OR for going 67 in a construction zone. I was told by the officer to follow one of the options on the back of the ticket. One of thoise is to plea guilty and pay the amount written for the infraction on the front of the ticket. That area is blank. Does it mean I get to ple guilty and pay the amount on the front, $0.