The circuit shown below consists of a battery of negligible internal resistance and two resistors,

(${R}_{1}= \text{ 6.0 Ohms and } {R}_{2}$). The resistance of the connecting wires is also negligible.

- The current entering point X in the circuit is $3.0\text{ Amps}$.
- The current leaving point X and going into the lower 'branch' (containing ${R}_{2}$) is $1.0\text{ Amp}$.

Which of the following is the value of ${R}_{2}$?