I've been trying to re-arrange this equation to solve for R instead of A, but I can't seem to get it past being self-referential, and if I assign values to the variables, and recalculate with my re-arrangements, I get different answers, which indicates to me that I'm doing something wrong. Here's the equation:
I figure the first step should be:
But that is about as far as I can get. How can I get R all on one side of the equation?