The measurement system depicted in the figure below consists of a resistive Wheatstone bridge excited by a dc current. To establish the excitation current in this configuration, a zener diode is employed, with . The zener is considered here as an ideal device, operating in regulation with a current through its terminals of 5.3 mA.

Assume , , , . In the Wheatstone bridge consider and  mΩ/Ω.

Determine the common-voltage at the bridge output (i.e., the common-mode voltage of and ).