Answer
$5.09pC$
Work Step by Step
First of all, we find the total electric flux as
$\phi=\phi_1+\phi_2+\phi_3+\phi_4+\phi_5+\phi_6$
$\implies \phi=150.0+250.0-350.0+175.0-100.0+450.0=575.0\frac{Nm^2}{C}$
Now we can find the total charge as
$q=\epsilon{\circ}\phi$
We plug in the known values to obtain:
$q=(8.85\times 10^{-12})(575.0)$
$q=5.09\times 10^{-9}=5.09pC$
