Solving for offset "x"

So, I'm trying to work on the measurements for cutting the sheet of plywood. It lays out really nice until you get to one irritating little detail. What is the exact offset point on the 16" wide panel? The 8" panel is straight on one side, so no thinking there. The other panel comes to a point a little bit away from the edge. When the measurement is taken off the graph paper, it comes to about 2.5". This seemed good enough for the model and probably even for plywood so why bother?

It really started to bug me when I thought of making the cut drawing into a bitmap so I could give it to a customer of mine. He has a machine that I believe is called a flying router something. You throw in a sheet of plywood, a vacumm sucks it down and a bit comes out and cuts it perfect everytime. I thought of giving him 4 or 6 sheets of plywood and letting him cut them for me, perfectly.

When preparing for this, I stared at the halfbreth and tried to find two sides and an angle or two angles and a side, without success. With the right angle of the 8" side, the three side measurements locked in and the right angle between the top and the verticle, I can't imagine it moving or having any variables. Yet I still can't figure it out. I even asked my High School Junior, who right away denied knowing how to do it or even having a clue, despite taking pre-calc.

So, I'm reaching out to anybody who can help me solve for "x".