The currents flowing at points X and Y are to be found; and the p.d. between points X and Z is to be found. Find the joint resistance of the parallel network. Then with the total resistance of circuit and supply voltage (I= V/R) find the current at X. The voltage across the shunt network is known and using Ohm's law (I=V/R) find the current through point Y. Subtract the voltage across the 2-ohm resistor (found using V=IR) from the total voltage to find the voltage across X and Z.