In the circuit of Fig, the 5.0-Ω resistor is removed and replaced by a resistor of unknown

Question:

In the circuit of Fig, the 5.0-Ω resistor is removed and replaced by a resistor of unknown resistance R. When this is done, an ideal voltmeter connected across the points b and c reads 1.9 V. Find
(a) The current in the circuit and
(b) The resistance R.
(c) Graph the potential rises and drops in this circuit (see Fig).