Calculating resistance, voltage, and current using Ohm's law

A student builds a simple circuit with a single resistor with resistance $2R$2, R and measures an electric potential difference $\Delta V$delta, V across the resistor. Then, the student replaces the resistor with a new one of resistance $\dfrac{R}{2}$start fraction, R, divided by, 2, end fraction and keeps the electric potential difference the same.