What is the voltage across the 6 Ω resistor?
The right-hand side of the circuit, consisting of the two 10 Ω resistors and the 5 Ω resistor, is irrelevant insofar as the determination of voltage across the 6 Ω resistor is concerned.
Parallel combination of the two 8 Ω resistors results in an equivalent resistance of 4 Ω as follows:
Using voltage division, the voltage across the 6 Ω resistor would be as follows:
V_{6 Ω}=(10 V).\left\lgroup\frac{6 Ω}{4 Ω+6 Ω}\right\rgroup=6 V