Answer
$q=-4.2\times 10^{-10}C$
Work Step by Step
We know that:
$\phi=\frac{q}{\epsilon_{\circ}}$
This can be rearranged as:
$q=\epsilon_{\circ}\phi$
We plug in the known values to obtain:
$q=8.85\times 10^{-12}\times (-48)=-4.2\times 10^{-10}C$
