In school I "learnt" that Ohm's law consists of three equations \begin{align} U &= R \cdot I \tag1 \\ R &= U / I \tag2 \\ I &= U / R \tag3 \end{align} In the eq.(1) the independent variables are $(R, I)$, in eq.(2) the independent variables are $(U, I)$, and in eq.(3) the independent variables are $(U, R)$. However, once you learn how to manipulate relationships Ohm's law actually is only one of the three upper mentioned equations: Two variables are input parameters (=know value, which is also called independent variable), while the last variable is the output (=unknown value, which is also called dependent variable). There exist no unique way to define dependent/independent variables, because these "names" depend on the used equation.

In school I "learnt" that Ohm's law consists of three equations \begin{align} U &= R \cdot I \tag1 \\ R &= U / I \tag2 \\ I &= U / R \tag3 \end{align} In the eq.(1) the independent variables are $(R, I)$, in eq.(2) the independent variables are $(U, I)$, and in eq.(3) the independent variables are $(U, R)$.

Once we learn how to manipulate relationships Ohm's law reduces to a single relationship -- each of the three equations will do. Each equation has two input variables (=know values, which are also called independent variables) and only one output variable   (=unknown value, which is also called dependent variable). There exist no unique way to define dependent/independent variables, because these "names" depend on the used equation.