Problem:

A gravity board for locating the center of gravity of a person consists of a horizontal board supported by a fulcrum at one end and by a scale at the other end. A physics student lies horizontally on the board with the top of his head above the fulcrum point. The scale is 2m from the fulcrum. The stuent has a mass of 70kg and when he is on the gravity board, the scale advances 250N. Where is the center of gravity of the student?

Okay, I have the answer to this question because I have a study guide along with the textbook, but I can't follow the steps... Does anyone know of a more logical step progression on how to work this problem?