Finding the voltage across capacitor?
Why won't the voltage across the Capacitance be affected by the 50ohms [resistor]

Since the question asks you to consider DC conditions, the current through the 50 ohm resistor is 0 (because it is in series with a capacitor). Therefore the voltage across it is also 0.

... and 10ohms resistor?

The voltage across the 10 ohm resistor affects the current through the 20 ohm resistor, and therefore it does affect the voltage across &quot;the capacitor&quot; (which I put in quotes because there are two capacitors in your circuit, so you should be more careful in naming them).