Solving for R2 (or X if that helps)

Hello everybody,

I'm working on a micro-controller to measure resistance with an equation that looks like this.

Ao = (R2/ R1+R2)*Vin

Now to make this work with my micro-controller I populate R1 to a known state of 10,000 and Vin to 3.3. What I measure with the micro-controller goes into Ao so I know everything except R2.

I first begin my simplification by dividing Ao by 3.3 leaving me with the following:

R2/10,000 + R2 = Ao /3.3

This is where my math breaks down. I'm not sure how to move R2 out (or move 10,000) out.

I tried populating R2 with a known value and then trying to work out how I could move the numbers to get R2 alone on one side but this didn't work. Closest I got was:

2/6+2 = 1/4 (assuming that 2 is my R2 value)

Any pointers as to how I go about moving R2 would be very helpful. Thanks.