Two point charges are enclosed by a spherical conducting shell that has an inner and outer radius of $13.0$ and $15.2 mathrm{~cm}$, respectively. One point charge has a charge of $q_{1}=8.30 mu mathrm{C}$, while the second point charge has an unknown charge $q_{2}$. The conducting shell is known to have a net electric charge of $-2.40 mu mathrm{C}$, but measurements find that the charge on the outer shell is $+3.70 mu mathrm{C}$. Determine the charge $q_{2}$ of the second point charge.