I assume the question refers to 4 L of gas, and asks for the new volume after the pressure and the temperature are doubled.
This can be solved by using the combined gas law,
You start with a pressure of
So, we can determine
It's evident that
This would have also been the case if the question said 4 moles of gas, since the combined gas law assumes that the number of moles is constant.
You would get the same result,
SInce the question provides a value for