Question 111472
The volume V of a gas varies inversely as the pressure P on it.
{{{V=k/P}}} where k is a constant. 
You can find the constant or re-write the equation another way.
{{{PV=k}}} where the product of pressure and volume equals the constant. 
And then, 
{{{P[1]V[1]=P[2]V[2]}}}
Substituting your values, 
{{{23*240=30*V[2]}}}
{{{V[2]=23*240/30}}}
{{{V[2]=184}}}
The volume is then 184 cc.