The new volume would be 225 mL. Half the volume at twice the pressure.
This behaves according to Boyle's law which tells us that the volume of a gas and its pressure are inversely proportional. That means if one is doubled, the other is reduced by a factor of two. Triple the pressure, and the volume is one-third of what it was before.
In equation form:
In your problem, the doubling of the pressure can be taken to mean
Now, the equation reads
So, there is our result. If