Given the equation
To write this equation in terms of R, you have to leave this term on one side of the equal sign and all other terms must be on the other side.
To "pass" one term from one side of the = sign to the other side, you have to apply the opposite operation. The terms "n" and "T" are multiplying "R", so to pass them to the other side of the equal sign you have to divide both sides by "nT"
The expression written for R is