It's very difficult, if not impossible, to solve R. R represents the postflop value of your hand, all of the profitable bluffs, value bets, and semibluffs you'll be making, subtracting all of the mistakes you make. It will be higher if your hand makes strong, dominating pairs, or if its suited or connected, or if your range is very strong otherwise and you'll thus be able to make a lot of profitable bluffs. The best you can do is estimate R, and the more you play the more you'll get a feel for how profitable your hands are to play.