Newton’s first law says a body at rest will remain at rest unless acted upon by an outside force, and a body in motion will continue in motion at the same speed and in the same direction unless acted upon by an outside force. what forces were acting on the marble as it traveled down the ramp?

See below.

Explanation:

You didn't provide a picture or any other real information. And while I usually wouldn't answer questions like that, simply because I couldn't without more info, I think I can give insight to this pretty quickly.

If we're assuming a marble is moving down a ramp in a realistic situation:

-the force of gravity is what makes it go down the ramp to begin with

-the force of friction makes the marble roll and eventually stop

-there may also be air friction acting on the marble, though it wouldn't be very noticeable unless it was going abnormally fast... or down a really, really large ramp I guess