How do I calculate length of bridge on this one?

A hiker who weights 985 N is strolling thru the woods and crosses a small horizontal bridge. The bridge is uniform, weights 3610N and rests on two concrete supports, one at each end. He stops 1/5th of the way along the bridge. What is the magnitude of the force that a concrete support exerts on the bridge First at the near end and at the for end???

How do I do this with no length of the bridge.

I am lost on this one.

Can someone help please.

I know he goes 1/5th, but how does that give me a distance??