Why Ohm's Law says current equals voltage divided by resistance, I = E / R, where E is in volts, R in ohms and I in amperes. Raising the voltage across a fixed resistance raises the current proportionally, while raising the resistance for a fixed voltage cuts the current down. The same relationship rearranges to E = I x R and R = E / I, so all three forms come from one equation.
Watch out Multiplying voltage by resistance is the tempting trap, but that gives no meaningful quantity here; multiplication belongs in E = I x R, where current and resistance are multiplied. Choices with E squared come from power formulas like P = E squared / R, not current.
Draw the triangle: E on top, I and R below. Cover what you want. Cover I and you see E over R.